feat: Tandoor integration — settings, test connection, import, duplicate detection

Add TandoorClient (app/tandoor.py) with full recipe creation, image upload,
and duplicate detection via the Tandoor REST API. Settings page now has
separate Mealie and Tandoor sections. Import page shows both send buttons
based on which services are configured.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/config.py

@@ -1,4 +1,4 @@
-"""Configuration management — persists Mealie connection settings to a JSON file."""
+"""Configuration management — persists Mealie and Tandoor connection settings to a JSON file."""
 
 import json
 import os
@@ -7,13 +7,16 @@ from pathlib import Path
 DATA_DIR = Path(os.environ.get("DATA_DIR", "/data"))
 CONFIG_FILE = DATA_DIR / "config.json"
 
-# Optional internal URL for Docker-to-Docker API calls (avoids Cloudflare hairpin).
-# The user-facing mealie_url is still used for browser links.
+# Optional internal URLs for Docker-to-Docker API calls (avoids Cloudflare hairpin).
+# The user-facing URLs are still used for browser links.
 MEALIE_INTERNAL_URL = os.environ.get("MEALIE_INTERNAL_URL", "").strip().rstrip("/")
+TANDOOR_INTERNAL_URL = os.environ.get("TANDOOR_INTERNAL_URL", "").strip().rstrip("/")
 
 _DEFAULTS = {
     "mealie_url": "",
     "mealie_api_key": "",
+    "tandoor_url": "",
+    "tandoor_api_key": "",
 }