feat(navi): deployment profiles + /api/config endpoint

Add profile-driven config infrastructure:
- config/profiles/{home,regional_pi,minimal_pi}.yaml templates
- lib/deployment_config.py loader (reads RECON_PROFILE env var)
- GET /api/config returns active profile as JSON (5min cache)

Frontend reads this on startup to determine tile source, defaults,
and feature flags. No existing behavior changed.

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

lib/api.py

@@ -24,6 +24,7 @@ from werkzeug.utils import secure_filename
 
 from .utils import get_config, content_hash, clean_filename_to_title, derive_source_and_category, generate_download_url, setup_logging
 from .status import StatusDB
+from .deployment_config import get_deployment_config
 
 logger = setup_logging('recon.api')
 
@@ -1165,6 +1166,15 @@ def api_knowledge_stats():
     return jsonify(_cache['knowledge_stats'])
 
 
+@app.route('/api/config')
+def api_config():
+    """Return deployment profile config for frontend consumption."""
+    config = get_deployment_config()
+    resp = jsonify(config)
+    resp.headers['Cache-Control'] = 'public, max-age=300'
+    return resp
+
+
 @app.route('/api/health')
 def api_health():
     """Health check endpoint for monitoring."""