feat(navi): add netsyms tier-2 geocoding + geocode API

Add Netsyms AddressDatabase2025 (159M US+CA addresses) as tier-2
in the geocode chain: address_book → netsyms → photon.

- lib/netsyms.py: SQLite lookup module (lazy, read-only, thread-safe)
- lib/netsyms_api.py: Flask blueprints for /api/netsyms/* and /api/geocode
- lib/netsyms_test.py: 7 test cases (street, free-text, zipcode, health)
- lib/nav_tools.py: new geocode() with consistent {name,lat,lon,source,raw}
- lib/api.py: register netsyms_bp and geocode_bp

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

lib/netsyms_api.py

@@ -0,0 +1,48 @@
+"""
+RECON Netsyms API + Geocode chain — Flask Blueprints.
+
+GET /api/netsyms/lookup?q=<free text>&country=<optional>
+GET /api/netsyms/health
+GET /api/geocode?q=<query>   (full 3-tier chain: address_book → netsyms → photon)
+"""
+
+from flask import Blueprint, request, jsonify
+
+from . import netsyms
+from . import address_book
+from . import nav_tools
+from .utils import setup_logging
+
+logger = setup_logging('recon.netsyms_api')
+
+netsyms_bp = Blueprint('netsyms', __name__)
+geocode_bp = Blueprint('geocode', __name__)
+
+
+@netsyms_bp.route('/api/netsyms/lookup')
+def api_netsyms_lookup():
+    q = request.args.get('q', '').strip()
+    if not q:
+        return jsonify({'error': 'Missing q parameter'}), 400
+
+    country = request.args.get('country', '').strip() or None
+    results = netsyms.lookup_free_text(q, country_hint=country)
+    return jsonify({'results': results, 'count': len(results), 'query': q})
+
+
+@netsyms_bp.route('/api/netsyms/health')
+def api_netsyms_health():
+    return jsonify(netsyms.health())
+
+
+@geocode_bp.route('/api/geocode')
+def api_geocode():
+    q = request.args.get('q', '').strip()
+    if not q:
+        return jsonify({'error': 'Missing q parameter'}), 400
+
+    result = nav_tools.geocode(q)
+    if result is None:
+        return jsonify({'error': 'No results', 'query': q}), 404
+
+    return jsonify(result)