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.

tests/Controller/LoginControllerTest.php

@@ -19,6 +19,24 @@ final class LoginControllerTest extends AbstractControllerWebTestCase
         self::assertSelectorExists('form');
     }
 
+    public function testNavbarTogglerHasNoDeadTargetWhenNotAuthenticated(): void
+    {
+        $this->client->request(Request::METHOD_GET, '/login');
+
+        $crawler = $this->client->getCrawler();
+        $toggler = $crawler->filter('.navbar-toggler');
+
+        if (0 === $toggler->count()) {
+            self::assertSelectorNotExists('#navbarSupportedContent');
+
+            return;
+        }
+
+        $target = $toggler->attr('data-bs-target');
+        $this->assertNotNull($target);
+        self::assertSelectorExists($target);
+    }
+
     public function testLoginRedirectsToBackofficeWhenAlreadyAuthenticated(): void
     {
         $this->loginAs('test@example.org');