Add Taskfile for unified dev workflow across all components (#6080)

## Add Taskfile for unified dev workflow

### Summary
- Introduces [Taskfile](https://taskfile.dev/) as the single CLI entry
point for all development workflows across backend, frontend, engine,
Docker, and desktop
- ~80 tasks organized into 6 namespaces: `backend:`, `frontend:`,
`engine:`, `docker:`, `desktop:`, plus root-level composites
- All CI workflows migrated to use Task
- Deletes `engine/Makefile` and `scripts/build-tauri-jlink.{sh,bat}` —
replaced by Task equivalents
- Removes redundant npm scripts (`dev`, `build`, `prep`, `lint`, `test`,
`typecheck:all`) from `package.json`
- Smart dependency caching: `sources`/`status`/`generates`
fingerprinting, CI-aware `npm ci` vs `npm install`, `run: once` for
parallel dep deduplication

### What this does NOT do
- Does not replace Gradle, npm, or Docker — Taskfile is a thin
orchestration wrapper
- Does not change application code or behavior

### Install
```
npm install -g @go-task/cli    # or: brew install go-task, winget install Task.Task
```

### Quick start
```
task --list       # discover all tasks
task install      # install all deps
task dev          # start backend + frontend
task dev:all      # also start AI engine
task test         # run all tests
task check        # quick quality gate (local dev)
task check:all    # full CI quality gate
```

### Test plan
- [ ] Install `task` CLI and run `task --list` — verify all tasks
display
- [ ] Run `task install` — verify frontend + engine deps install
- [ ] Run `task dev` — verify backend + frontend start, Ctrl+C exits
cleanly
- [ ] Run `task frontend:check` — verify typecheck + lint + test pass
- [ ] Run `task desktop:dev` — verify jlink builds are cached on second
run
- [ ] Verify CI passes on all workflows

---------

Co-authored-by: James Brunton <[email protected]>

AGENTS.md

@@ -2,18 +2,40 @@
 
 This file provides guidance to AI Agents when working with code in this repository.
 
+## Taskfile (Recommended)
+
+This project uses [Task](https://taskfile.dev/) as a unified command runner. All build, dev, test, lint, and docker commands can be run from the repo root via `task <command>`. Run `task --list` to see all available commands.
+
+### Quick Reference
+- `task install` — install all dependencies
+- `task dev` — start backend + frontend concurrently
+- `task dev:all` — start backend + frontend + engine concurrently
+- `task build` — build all components
+- `task test` — run all tests (backend + frontend + engine)
+- `task lint` — run all linters
+- `task format` — auto-fix formatting across all components
+- `task check` — full quality gate (lint + typecheck + test)
+- `task clean` — clean all build artifacts
+- `task docker:build` — build standard Docker image
+- `task docker:up` — start Docker compose stack
+
 ## Common Development Commands
 
 ### Build and Test
-- **Build project**: `./gradlew clean build`
-- **Run locally**: `./gradlew bootRun`
-- **Full test suite**: `./test.sh` (builds all Docker variants and runs comprehensive tests)
-- **Code formatting**: `./gradlew spotlessApply` (runs automatically before compilation)
+- **Build project**: `task build`
+- **Run backend locally**: `task backend:dev`
+- **Run all tests**: `task test` (or individually: `task backend:test`, `task frontend:test`, `task engine:test`)
+- **Docker integration tests**: `./test.sh` (builds all Docker variants and runs comprehensive tests)
+- **Code formatting**: `task format` (or `task backend:format` for Java only)
+- **Full quality gate**: `task check` (runs lint + typecheck + test across all components)
 
 ### Docker Development
-- **Build ultra-lite**: `docker build -t stirlingtools/stirling-pdf:latest-ultra-lite -f ./Dockerfile.ultra-lite .`
-- **Build standard**: `docker build -t stirlingtools/stirling-pdf:latest -f ./Dockerfile .`
-- **Build fat version**: `docker build -t stirlingtools/stirling-pdf:latest-fat -f ./Dockerfile.fat .`
+- **Build standard**: `task docker:build` (or `docker build -t stirling-pdf -f docker/embedded/Dockerfile .`)
+- **Build fat version**: `task docker:build:fat`
+- **Build ultra-lite**: `task docker:build:ultra-lite`
+- **Start compose stack**: `task docker:up` (or `task docker:up:fat`, `task docker:up:ultra-lite`)
+- **Stop compose stack**: `task docker:down`
+- **View logs**: `task docker:logs`
 - **Example compose files**: Located in `exampleYmlFiles/` directory
 
 ### Security Mode Development
@@ -23,20 +45,22 @@ Set `DOCKER_ENABLE_SECURITY=true` environment variable to enable security featur
 Development for the AI engine happens in the `engine/` folder. The frontend calls the Python via Java as a proxy.
 
 - Follow the engine-specific guidance in [engine/AGENTS.md](engine/AGENTS.md) for Python architecture, code style, and AI usage.
-- Use Makefile commands for Python work:
-  - From `engine/`: `make check` to lint, type-check, test, etc. and `make fix` to fix easily fixable linting and formatting issues.
-- The project structure is defined in `engine/pyproject.toml`. Any new dependencies should be listed there, followed by running `make install`.
+- Use Task commands from the repo root:
+  - `task engine:check` — lint, type-check, test
+  - `task engine:fix` — auto-fix linting and formatting
+  - `task engine:install` — install dependencies
+- The project structure is defined in `engine/pyproject.toml`. Any new dependencies should be listed there, followed by running `task engine:install`.
 
 ### Frontend Development
-- **Frontend dev server**: `cd frontend && npm run dev` (requires backend on localhost:8080)
+- **Frontend dev server**: `task frontend:dev` — requires backend on localhost:8080
 - **Tech Stack**: Vite + React + TypeScript + Mantine UI + TailwindCSS
 - **Proxy Configuration**: Vite proxies `/api/*` calls to backend (localhost:8080)
 - **Build Process**: DO NOT run build scripts manually - builds are handled by CI/CD pipelines
-- **Package Installation**: DO NOT run npm install commands - package management handled separately
+- **Package Installation**: `task frontend:install`
 - **Deployment Options**:
-  - **Desktop App**: `npm run tauri-build` (native desktop application)
-  - **Web Server**: `npm run build` then serve dist/ folder
-  - **Development**: `npm run tauri-dev` for desktop dev mode
+  - **Desktop App**: `task desktop:build`
+  - **Web Server**: `task frontend:build` then serve dist/ folder
+  - **Development**: `task desktop:dev` for desktop dev mode
 
 #### Environment Variables
 - All `VITE_*` variables must be declared in the appropriate example file:
@@ -44,8 +68,8 @@ Development for the AI engine happens in the `engine/` folder. The frontend call
   - `frontend/config/.env.saas.example` — SaaS-only vars
   - `frontend/config/.env.desktop.example` — desktop (Tauri)-only vars
 - Never use `|| 'hardcoded-fallback'` inline — put defaults in the example files
-- `npm run prep` / `prep:saas` / `prep:desktop` auto-create the env files from examples on first run, and error if any required keys are missing
-- These prep scripts run automatically at the start of all `dev*`, `build*`, and `tauri*` commands
+- `task frontend:prep` / `prep:saas` / `prep:desktop` auto-create the env files from examples on first run, and error if any required keys are missing
+- Prep runs automatically as a dependency of all `dev*`, `build*`, and `desktop*` tasks
 - See `frontend/README.md#environment-variables` for full documentation
 
 #### Import Paths - CRITICAL
@@ -299,15 +323,17 @@ The frontend is organized with a clear separation of concerns:
 
 ## Development Workflow
 
-1. **Local Development**:
-   - Backend: `./gradlew bootRun` (runs on localhost:8080)
-   - Frontend: `cd frontend && npm run dev` (runs on localhost:5173, proxies to backend)
-2. **Docker Testing**: Use `./test.sh` before submitting PRs
-3. **Code Style**: Spotless enforces Google Java Format automatically
-4. **Translations**:
+1. **Local Development** (using Taskfile):
+   - Backend + frontend: `task dev`
+   - All services (including AI engine): `task dev:all`
+   - Or individually: `task backend:dev` (localhost:8080), `task frontend:dev` (localhost:5173), `task engine:dev` (localhost:5001)
+2. **Quality Gate**: Run `task check` before submitting PRs
+3. **Docker Testing**: Use `./test.sh` for full Docker integration tests
+4. **Code Style**: Spotless enforces Google Java Format automatically (`task backend:format`)
+5. **Translations**:
    - Backend: Use helper scripts in `/scripts` for multi-language updates
    - Frontend: Update JSON files in `frontend/public/locales/` or use conversion script
-5. **Documentation**: API docs auto-generated and available at `/swagger-ui/index.html`
+6. **Documentation**: API docs auto-generated and available at `/swagger-ui/index.html`
 
 ## Frontend Architecture Status