refactor : simplify codebase and fix critical issues

Backend:
- Add MCP Serializer to centralize entity-to-array conversion (~300 lines deduped)
- Fix race condition in task/ticket number generation (SELECT FOR UPDATE + transaction)
- Add unique constraint on task (project_id, number) with migration
- Fix MIME type validation: use server-detected finfo instead of client-supplied type
- Add allowlist of permitted MIME types for uploads
- Fix TaskDocumentDownloadController: allow ROLE_CLIENT access, add priority:1
- Fix notification sent even when ticket status unchanged
- Remove redundant exception constructors
- Simplify services (BookStackApi double fetch, TokenEncryptor, GiteaApi)
- Consolidate duplicate checks in processors

Frontend:
- Fix useApi isHandlingUnauthorized scope (module-level to prevent double 401 redirect)
- Fix client-tickets toast key copy-paste bug
- Merge duplicated tasks service methods (getByProject + getByProjectArchived)
- Extract shared uploadWithRelation helper in task-documents service
- Extract formatFileSize utility from duplicated component code
- Extract status transition logic into useClientTicketHelpers composable
- Remove dead code (unused router, handleLogout, empty script blocks)
- Merge duplicate watchers and onMounted calls
- Normalize arrow functions to function declarations per convention

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Mcp/Tool/TimeEntry/UpdateTimeEntryTool.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace App\Mcp\Tool\TimeEntry;
 
+use App\Mcp\Tool\Serializer;
 use App\Repository\ProjectRepository;
 use App\Repository\TaskRepository;
 use App\Repository\TaskTagRepository;
@@ -83,29 +84,6 @@ class UpdateTimeEntryTool
 
         $this->entityManager->flush();
 
-        return json_encode([
-            'id'        => $entry->getId(),
-            'title'     => $entry->getTitle(),
-            'startedAt' => $entry->getStartedAt()?->format('c'),
-            'stoppedAt' => $entry->getStoppedAt()?->format('c'),
-            'duration'  => $entry->getStoppedAt() && $entry->getStartedAt()
-                ? (int) round(($entry->getStoppedAt()->getTimestamp() - $entry->getStartedAt()->getTimestamp()) / 60)
-                : null,
-            'user'    => ['id' => $entry->getUser()->getId(), 'username' => $entry->getUser()->getUsername()],
-            'project' => $entry->getProject() ? [
-                'id'   => $entry->getProject()->getId(),
-                'code' => $entry->getProject()->getCode(),
-                'name' => $entry->getProject()->getName(),
-            ] : null,
-            'task' => $entry->getTask() ? [
-                'id'     => $entry->getTask()->getId(),
-                'number' => $entry->getTask()->getNumber(),
-                'title'  => $entry->getTask()->getTitle(),
-            ] : null,
-            'tags' => $entry->getTags()->map(fn ($t) => [
-                'id'    => $t->getId(),
-                'label' => $t->getLabel(),
-            ])->toArray(),
-        ]);
+        return json_encode(Serializer::timeEntry($entry));
     }
 }