feat: Add MinIO file listing and document reading endpoints (BRIC-9)

[Kaiohz]

Summary

• Add GET /api/v1/files/list endpoint and list_files MCP tool to browse MinIO files without indexing
• Add POST /api/v1/files/read endpoint and read_file MCP tool to extract text content from MinIO files using Kreuzberg (91 file formats)
• Follow hexagonal architecture: DocumentReaderPort → KreuzbergAdapter, StoragePort.list_files_metadata() → MinioAdapter
• Add path traversal validation, proper error handling (404/422), and temp file cleanup
• 153 unit tests pass, 12 QA integration tests pass, SonarQube clean, ruff/lint clean

Acceptance Criteria Met

AC	Status
AC1: List Files MCP Tool	✅ Returns object_name, size, last_modified
AC2: Read File MCP Tool	✅ Downloads from MinIO, extracts via Kreuzberg
AC3: List Files REST Endpoint	✅ GET /api/v1/files/list
AC4: Read File REST Endpoint	✅ POST /api/v1/files/read
AC5: Error Handling	✅ 404 for missing files, 422 for unsupported formats/path traversal
AC6: Hexagonal Architecture	✅ DocumentReaderPort + KreuzbergAdapter, ports-and-adapters
AC7: Performance	✅ Temp files cleaned up, async extraction

Definition of Done

• Code implemented following hexagonal architecture
• Unit tests written (TDD approach)
• Full test suite passes (153 passed)
• Linter passes (ruff check + format)
• Code review approved
• SonarQube: 0 new issues (only pre-existing ones remain)
• Trivy: 0 new vulnerabilities
• Manual testing completed (12/12 QA tests pass)
• README updated with new endpoints/tools documentation
• PR created
• DO NOT MERGE (per ticket DoD)

[Kaiohz]

🟢 Code Review — BRIC-9: MinIO file listing & Kreuzberg reading

✅ Points positifs

• Architecture exemplaire : DocumentReaderPort → KreuzbergAdapter, StoragePort.list_files_metadata() → MinioAdapter
• 153 tests unitaires + 12 QA integration tests
• Path traversal validation sur file_path (bloque .. et chemins absolus)
• Temp file cleanup avec contexte async
• Error handling complet : 404 (not found), 422 (unsupported/traversal)
• DoD rigoureux : review, SonarQube, Trivy, manual QA

⚠️ Points d'attention

1. Pas de timeout configurable sur l'extraction Kreuzberg — un gros fichier pourrait bloquer indéfiniment

Score de confiance : 9/10 👍