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]>

.github/workflows/frontend-backend-licenses-update.yml

@@ -89,12 +89,13 @@ jobs:
           NPM_CONFIG_IGNORE_SCRIPTS: "true"
         run: npm ci --ignore-scripts --audit=false --fund=false
 
+      - name: Install Task
+        uses: go-task/setup-task@3be4020d41929789a01026e0e427a4321ce0ad44 # v2.0.0
       - name: Generate frontend license report (internal PR)
         if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork == false
-        working-directory: frontend
         env:
           PR_IS_FORK: "false"
-        run: npm run generate-licenses
+        run: task frontend:licenses:generate
 
       - name: Generate frontend license report (fork PRs, pinned)
         if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork == true
@@ -341,15 +342,11 @@ jobs:
         with:
           gradle-version: 9.3.1
 
+      - name: Install Task
+        uses: go-task/setup-task@3be4020d41929789a01026e0e427a4321ce0ad44 # v2.0.0
       - name: Check licenses and generate report
         id: license-check
-        run: |
-          # NOTE: --no-parallel is intentional here. Running the license-checking tasks in parallel has
-          # previously caused intermittent concurrency issues in CI (e.g. flaky failures in the license
-          # plugin/Gradle when multiple projects are evaluated concurrently). Disabling parallelism trades
-          # some build speed for more reliable license reports. If the underlying issues are resolved in
-          # future Gradle or plugin versions, this flag can be reconsidered.
-          ./gradlew checkLicense generateLicenseReport --no-parallel || echo "LICENSE_CHECK_FAILED=true" >> $GITHUB_ENV
+        run: task backend:licenses:generate || echo "LICENSE_CHECK_FAILED=true" >> $GITHUB_ENV
         env:
           MAVEN_USER: ${{ secrets.MAVEN_USER }}
           MAVEN_PASSWORD: ${{ secrets.MAVEN_PASSWORD }}