feat(time-tracking) : migrate TimeEntry into TimeTracking module (back)

First business module of Phase 2 (LST-64, rodage). Strangler-style,
additive move — no behavioural change to the public API or MCP tools.

- New module App\Module\TimeTracking (TimeTrackingModule, id "time-tracking",
  declares time-tracking.entries.view/export permissions in the RBAC catalog;
  operation security left on ROLE_USER, not re-wired here).
- Move TimeEntry entity, repository (now interface + Doctrine impl bound in
  services.yaml), ActiveTimeEntryProvider, export service/controller and the
  4 MCP TimeEntry tools into the module. #[ApiResource] (operations, security,
  uriTemplates /time_entries/*), filters and serialization groups preserved.
- Doctrine mapping "TimeTracking" added; table time_entry unchanged.
- Sidebar item gated with module "time-tracking" (SidebarFilter disables the
  route when the module is inactive).
- Timestampable/Blamable adopted (first adopter): additive migration adds
  created_at/updated_at/created_by/updated_by (nullable, FK SET NULL) +
  COMMENT ON COLUMN. Functional test confirms created_at on persist and
  updated_at refresh on update — the suspected preUpdate recompute issue does
  not occur (Doctrine ORM 3.6.2 recomputes change sets after preUpdate).

159 tests green, schema mapping valid, php-cs-fixer clean.

config/modules.php

@@ -8,7 +8,9 @@ declare(strict_types=1);
  */
 
 use App\Module\Core\CoreModule;
+use App\Module\TimeTracking\TimeTrackingModule;
 
 return [
     CoreModule::class,
+    TimeTrackingModule::class,
 ];