Refactor gateway into modular architecture

Split 1878-line server.py into 15 focused modules:
- config.py: all env vars and constants
- database.py: schema, init, seed logic
- sessions.py: session/token CRUD
- proxy.py: proxy_request, SERVICE_MAP, resolve_service
- responses.py: ResponseMixin for handler helpers
- auth.py: login/logout/register handlers
- dashboard.py: dashboard, apps, connections, pinning
- command.py: AI command bar
- integrations/booklore.py: auth, books, cover, import
- integrations/kindle.py: send-to-kindle, file finder
- integrations/karakeep.py: save/delete bookmarks
- integrations/qbittorrent.py: download status
- integrations/image_proxy.py: external image proxy

server.py is now thin routing only (~344 lines).
All routes, methods, status codes, and responses preserved exactly.
Added PYTHONUNBUFFERED=1 to Dockerfile for live logging.

gateway/config.py

@@ -0,0 +1,61 @@
+"""
+Platform Gateway — Configuration constants and environment variables.
+"""
+
+import os
+import ssl
+from pathlib import Path
+
+# ── Server ──
+PORT = int(os.environ.get("PORT", 8100))
+DATA_DIR = Path(os.environ.get("DATA_DIR", "/app/data"))
+DB_PATH = DATA_DIR / "platform.db"
+
+# ── Service backends ──
+TRIPS_URL = os.environ.get("TRIPS_BACKEND_URL", "http://localhost:8087")
+FITNESS_URL = os.environ.get("FITNESS_BACKEND_URL", "http://localhost:8095")
+INVENTORY_URL = os.environ.get("INVENTORY_BACKEND_URL", "http://localhost:4499")
+NOCODB_API_TOKEN = os.environ.get("NOCODB_API_TOKEN", "")
+MINIFLUX_URL = os.environ.get("MINIFLUX_URL", "http://localhost:8767")
+MINIFLUX_API_KEY = os.environ.get("MINIFLUX_API_KEY", "")
+TRIPS_API_TOKEN = os.environ.get("TRIPS_API_TOKEN", "")
+SHELFMARK_URL = os.environ.get("SHELFMARK_URL", "http://shelfmark:8084")
+SPOTIZERR_URL = os.environ.get("SPOTIZERR_URL", "http://spotizerr-app:7171")
+BUDGET_URL = os.environ.get("BUDGET_BACKEND_URL", "http://localhost:3001")
+
+# ── Booklore (book library manager) ──
+BOOKLORE_URL = os.environ.get("BOOKLORE_URL", "http://booklore:6060")
+BOOKLORE_USER = os.environ.get("BOOKLORE_USER", "")
+BOOKLORE_PASS = os.environ.get("BOOKLORE_PASS", "")
+BOOKLORE_BOOKS_DIR = Path("/booklore-books")
+BOOKDROP_DIR = Path("/bookdrop")
+
+# ── SMTP2GO (email / Send to Kindle) ──
+SMTP2GO_API_KEY = os.environ.get("SMTP2GO_API_KEY", "")
+SMTP2GO_FROM_EMAIL = os.environ.get("SMTP2GO_FROM_EMAIL", "")
+SMTP2GO_FROM_NAME = os.environ.get("SMTP2GO_FROM_NAME", "Platform")
+KINDLE_EMAIL_1 = os.environ.get("KINDLE_EMAIL_1", "")
+KINDLE_EMAIL_2 = os.environ.get("KINDLE_EMAIL_2", "")
+KINDLE_LABELS = os.environ.get("KINDLE_LABELS", "Kindle 1,Kindle 2")
+
+# ── Karakeep (bookmarking) ──
+KARAKEEP_URL = os.environ.get("KARAKEEP_URL", "http://192.168.1.42:3005")
+KARAKEEP_API_KEY = os.environ.get("KARAKEEP_API_KEY", "")
+
+# ── AI ──
+OPENAI_API_KEY = os.environ.get("OPENAI_API_KEY", "")
+OPENAI_MODEL = os.environ.get("OPENAI_MODEL", "gpt-5.2")
+
+# ── Session config ──
+SESSION_MAX_AGE = int(os.environ.get("SESSION_MAX_AGE", 30 * 86400))  # 30 days
+
+# ── Shared state ──
+_booklore_token = {"access": "", "refresh": "", "expires": 0}
+
+# ── Ensure data dir exists ──
+DATA_DIR.mkdir(parents=True, exist_ok=True)
+
+# ── Shared SSL context (skip verification for internal services) ──
+_ssl_ctx = ssl.create_default_context()
+_ssl_ctx.check_hostname = False
+_ssl_ctx.verify_mode = ssl.CERT_NONE