fix: address final review findings for foundation plan

- C1: drop module-level app singleton in app/main.py so importing the
  package no longer validates Settings or creates DATA_DIR; run uvicorn
  with --factory in the Dockerfile. pytest now collects and passes with
  no ambient env vars.
- I2: add missing app/auth, app/security, app/web __init__.py so
  setuptools discovers all five packages.
- I3: resolve the Jinja2 template directory relative to __file__ instead
  of the process CWD.
- I4: add .gitignore covering .env, data/, .venv/, caches and build
  artifacts so example deployment secrets cannot be committed.
- I5: assert UserRepository.list_enabled() excludes disabled users.
- M6: encode both operands before hmac.compare_digest in validate_csrf so
  a non-ASCII token yields 403 instead of an unhandled 500.
- M9: remove unused relationship / HealthState imports.
- M11: make session cookie https_only configurable via SESSION_HTTPS_ONLY
  (default unchanged: false).
- M13: dispose SQLAlchemy engines in the db_session and client fixtures.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/web/routes.py

@@ -1,3 +1,5 @@
+from pathlib import Path
+
 from fastapi import APIRouter, Form, HTTPException, Request, status
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.templating import Jinja2Templates
@@ -10,7 +12,7 @@ from app.security.credentials import CredentialCipher
 from app.web.forms import UserFormData
 
 router = APIRouter()
-templates = Jinja2Templates(directory="app/web/templates")
+templates = Jinja2Templates(directory=str(Path(__file__).resolve().parent / "templates"))
 
 
 def _get_user_or_404(repository: UserRepository, user_id: int) -> SyncUser: