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/sidebar.php

@@ -22,7 +22,7 @@ return [
             ['label' => 'sidebar.general.dashboard', 'to' => '/', 'icon' => 'mdi:view-dashboard-outline'],
             ['label' => 'sidebar.general.myTasks', 'to' => '/my-tasks', 'icon' => 'mdi:clipboard-check-outline'],
             ['label' => 'sidebar.general.projects', 'to' => '/projects', 'icon' => 'mdi:folder-outline'],
-            ['label' => 'sidebar.general.timeTracking', 'to' => '/time-tracking', 'icon' => 'mdi:calendar-edit-outline'],
+            ['label' => 'sidebar.general.timeTracking', 'to' => '/time-tracking', 'icon' => 'mdi:calendar-edit-outline', 'module' => 'time-tracking'],
         ],
     ],
     [