Add Playwright/bootRun/test.sh tasks (#6244)

## Description

Consolidates Playwright running under cohesive Task namespaces, isolates
Playwright state from the developer's local working tree, and swaps CI's
frontend webserver from `vite` dev to `vite preview` against a pre-built
`dist/`.

### `e2e:*` namespace

Renames `.taskfiles/testing.yml` to `.taskfiles/e2e.yml` and
consolidates everything Playwright-related under one `e2e:` namespace:

- `e2e:stubbed` / `e2e:live` / `e2e:enterprise` / `e2e:cross-browser`:
project-specific runners
- `e2e:check` (no-Docker subset) and `e2e:check:all` (full)
- `e2e:oauth:up` / `:down`, `e2e:saml:up` / `:down`: symmetric lifecycle
for the keycloak compose stacks
- `e2e:install`: Playwright browser install
- `docker:test`: full Docker integration suite

The redundant `frontend:test:e2e:*` project shortcuts are removed. CI
workflows (`e2e-stubbed.yml`, `e2e-live.yml`, `build-enterprise.yml`,
`nightly.yml`) are updated to call the new task names.

### Isolated Playwright state

New `STIRLING_BASE_PATH` (and `-Dstirling.base-path=`) override in
`InstallationPathConfig` redirects the entire state tree (configs,
backups, customFiles, pipeline, logs) at startup. `task e2e:live` points
it at `.test-state/playwright/` (purged on every invocation) so the
suite never touches the developer's local DB, settings.yml or backups.

`task e2e:live` auto-spawns gradle, waits for `/api/v1/info/status` to
come up, runs Playwright, then tears down the whole backend process
tree.

### CI runs Playwright against `vite preview`

Builds the frontend up-front with `VITE_BUILD_FOR_PREVIEW=1` (forces
absolute base so deep SPA routes resolve `/assets/...`) and the
playwright `webServer` now uses `vite preview --port 5173 --strictPort`
in CI. Avoids the per-page on-demand transform cost that was blowing the
30s navigation timeout under `--workers=3` on
`all-tool-pages-load.spec.ts`. Local dev keeps `vite` dev for HMR.

### OAuth/SAML compose helpers

`start-oauth-test.sh` and `start-saml-test.sh` gain a `--license-key
<KEY>` (`-k`) flag so CI and scripted runs can skip the interactive
license prompt. `start-oauth-test.sh` also moves from `for arg in "$@"`
to a `while`-with-`shift` arg loop to support multi-arg flags
consistently with the SAML script.

### Backend gradlew unification

Drops the per-platform `cmd /c gradlew.bat` branches from `backend.yml`
and routes every gradle invocation through `bash gradlew`. Works
uniformly on Linux/macOS and Windows-with-Git-Bash.

### Compare.tsx flake fix (re-land of
[#6316](https://github.com/Stirling-Tools/Stirling-PDF/pull/6316))

Piggybacks Anthony's never-merged fix from #6316. Without it,
`e2e:stubbed` continues to flake under `--workers=3` on
`compare.spec.ts`'s second-upload case via a React "Maximum update depth
exceeded" infinite loop in the Compare auto-fill effect. CI traces from
recent failed runs match exactly; 10 local runs of `compare.spec.ts`
with `CI=1 --workers=3` pass cleanly with the fix applied.

---------

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

.github/workflows/e2e-stubbed.yml

@@ -28,9 +28,13 @@ jobs:
       - name: Install Task
         uses: go-task/setup-task@3be4020d41929789a01026e0e427a4321ce0ad44 # v2.0.0
       - name: Install Playwright (chromium only)
-        run: task frontend:test:e2e:install -- chromium
+        run: task e2e:install -- chromium
+      - name: Build frontend (production bundle for vite preview)
+        env:
+          VITE_BUILD_FOR_PREVIEW: "1"
+        run: task frontend:build
       - name: Run stubbed E2E tests (chromium)
-        run: task frontend:test:e2e -- --project=stubbed --workers=3
+        run: task e2e:stubbed -- --workers=3
       - name: Upload Playwright report
         if: always()
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1