Migrate frontend to TypeScript with Deno-based tooling (#209)

* Migrate frontend to TypeScript with Deno-based tooling (#206)

Compiles assets/*.ts via sensiolabs/typescript-bundle (standalone SWC
binary) and adds Deno for formatting, linting, type-checking, and
tests, keeping the project's no-Node/npm approach intact. Wires all
four into CI, the Justfile, and the pre-commit hook.

* fix: build TypeScript assets before running PHPUnit in CI

The tests job ran bin/console sass:build but never typescript:build,
so var/typescript/ didn't exist and any page rendering the importmap
(e.g. backoffice/base.html.twig) errored during tests.

* test: add regression test for backoffice navbar-toggler dead target

Guards against the navbar-toggler button pointing at a collapse
target (#navbarSupportedContent) that isn't rendered for the current
user — the bug hit on the login page before #210 restructured the
nav to always render at least one item (the Releases link) regardless
of auth state.

* fix: stop hand-enumerating TS files for deno check

deno check assets/*.ts assets/controllers/*.ts assets/controllers/bo/*.ts
was duplicated in CI and the Justfile, and silently misses any new
controller subdirectory (fmt/lint/test already recurse assets/ via
deno.json). Add a top-level exclude for assets/vendor/ (respected by
all deno subcommands, unlike the per-task include/exclude blocks) so
deno check assets/ can recurse safely instead.

* fix: GitHubReleasesService date parsing and falsy release name

- Move the release-mapping array_map inside the try block so a
  malformed published_at (or any other parse failure) degrades to the
  same empty-list fallback as an HTTP failure, instead of throwing
  uncaught out of the cache callback.
- Stop treating a release literally named "0" as unnamed — the old
  `?:` fallback is falsy for that string and silently substituted the
  tag name instead.
- Render release dates in UTC explicitly; Twig's date filter otherwise
  silently converts to the app's default timezone (Europe/Amsterdam),
  which could show the wrong calendar day for releases near midnight.

* docs: add scope-creep-as-a-service rule to CLAUDE.md

Per user instruction: when a review turns up a real bug outside the
current task's scope, fix it in the same MR (with a regression test)
rather than just reporting it, unless it needs a human design call.

.github/workflows/ci.yml

@@ -104,6 +104,22 @@ jobs:
             echo "::error::Translations are out of date. Run 'just translations' and commit the changes."
             exit 1
           fi
+      - name: TypeScript Formatting
+        id: ts_fmt
+        continue-on-error: true
+        run: docker compose exec -T php deno fmt --check assets/
+      - name: TypeScript Lint
+        id: ts_lint
+        continue-on-error: true
+        run: docker compose exec -T php deno lint assets/
+      - name: TypeScript Type Check
+        id: ts_check
+        continue-on-error: true
+        run: docker compose exec -T php deno check assets/
+      - name: TypeScript Tests
+        id: ts_test
+        continue-on-error: true
+        run: docker compose exec -T php deno test assets/
       - name: Check HTTP reachability
         run: curl -v --fail-with-body http://localhost
       - name: Assert all checks passed
@@ -123,6 +139,10 @@ jobs:
           check "PHPStan"          "${{ steps.phpstan.outcome }}"
           check "Rector"           "${{ steps.rector.outcome }}"
           check "Translations"     "${{ steps.translations.outcome }}"
+          check "TypeScript Formatting" "${{ steps.ts_fmt.outcome }}"
+          check "TypeScript Lint"       "${{ steps.ts_lint.outcome }}"
+          check "TypeScript Type Check" "${{ steps.ts_check.outcome }}"
+          check "TypeScript Tests"      "${{ steps.ts_test.outcome }}"
           exit $failed
 
   tests:
@@ -156,6 +176,8 @@ jobs:
         run: docker compose up php database --wait --no-build
       - name: Build SCSS
         run: docker compose exec -T php bin/console sass:build
+      - name: Build TypeScript
+        run: docker compose exec -T php bin/console typescript:build
       - name: Create test database
         run: docker compose exec -T php bin/console -e test doctrine:database:create
       - name: Run migrations