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/State/UserPasswordHasherProcessor.php

@@ -29,10 +29,10 @@ final readonly class UserPasswordHasherProcessor implements ProcessorInterface
      */
     public function process(mixed $data, Operation $operation, array $uriVariables = [], array $context = []): mixed
     {
-        if (null !== $data->getPassword() && !str_starts_with($data->getPassword(), '$')) {
-            $data->setPassword(
-                $this->passwordHasher->hashPassword($data, $data->getPassword())
-            );
+        $plainPassword = $data->getPassword();
+
+        if (null !== $plainPassword && !str_starts_with($plainPassword, '$')) {
+            $data->setPassword($this->passwordHasher->hashPassword($data, $plainPassword));
         }
 
         return $this->persistProcessor->process($data, $operation, $uriVariables, $context);