chore(compose): add shared json-file logging config and component labels

Introduce x-logging anchor with json-file driver, size/file caps, and
container name tagging so Alloy on puck can reliably tail every service
through the Docker socket. Apply to all services and inject
MNEMOSYNE_COMPONENT env vars (init/app/mcp/worker) for consistent log
attribution both

pyproject.toml

@@ -23,6 +23,7 @@ dependencies = [
     "pymemcache>=4.0,<5.0",
     "openai>=1.0,<2.0",
     "django-prometheus>=2.3,<3.0",
+    "python-json-logger>=3.0,<4.0",
     # Phase 2: Embedding Pipeline
     "PyMuPDF>=1.24,<2.0",
     "pymupdf4llm>=0.0.17,<1.0",