feat(navi): address book with geocoding integration

- YAML-backed saved locations (config/address_book.yaml)
- Exact/partial alias matching with case-insensitive lookup
- Flask blueprint: /api/address_book/lookup, /api/address_book/list
- Geocoder short-circuits Photon when address book has exact match
- Test suite for lookup behavior

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

lib/address_book.py

@@ -0,0 +1,132 @@
+"""
+RECON Address Book — YAML-backed saved-location lookup.
+
+Provides named locations (home, work, etc.) that short-circuit Photon
+geocoding when an exact alias match is found.
+
+Config: /opt/recon/config/address_book.yaml
+"""
+
+import os
+import threading
+
+import yaml
+
+from .utils import setup_logging
+
+logger = setup_logging('recon.address_book')
+
+_CONFIG_PATH = os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
+    'config', 'address_book.yaml',
+)
+
+_lock = threading.Lock()
+_entries: list[dict] = []
+_mtime: float = 0.0
+
+
+def _reload_if_changed():
+    """Reload the YAML file if its mtime has changed."""
+    global _entries, _mtime
+    try:
+        st = os.stat(_CONFIG_PATH)
+    except FileNotFoundError:
+        logger.warning("Address book not found: %s", _CONFIG_PATH)
+        _entries = []
+        _mtime = 0.0
+        return
+
+    if st.st_mtime == _mtime:
+        return
+
+    with _lock:
+        # Double-check after acquiring lock
+        try:
+            st = os.stat(_CONFIG_PATH)
+        except FileNotFoundError:
+            _entries = []
+            _mtime = 0.0
+            return
+        if st.st_mtime == _mtime:
+            return
+
+        with open(_CONFIG_PATH, 'r') as f:
+            data = yaml.safe_load(f) or {}
+
+        raw = data.get('entries', [])
+        loaded = []
+        for entry in raw:
+            # Normalise aliases to lowercase for matching
+            aliases = [a.lower() for a in entry.get('aliases', [])]
+            loaded.append({
+                'id': entry.get('id', ''),
+                'name': entry.get('name', ''),
+                'aliases': aliases,
+                'address': entry.get('address', ''),
+                'lat': entry.get('lat'),
+                'lon': entry.get('lon'),
+                'tags': entry.get('tags', []),
+            })
+        _entries = loaded
+        _mtime = st.st_mtime
+        logger.info("Address book loaded: %d entries from %s", len(_entries), _CONFIG_PATH)
+
+
+def load():
+    """Ensure the address book is loaded (and refreshed if the file changed)."""
+    _reload_if_changed()
+    return _entries
+
+
+def lookup(query: str):
+    """
+    Look up a query against name and aliases.
+
+    Returns dict with the matching entry plus a 'confidence' field:
+      - "exact": full name or alias match
+      - "partial": query is a substring of an alias or name (or vice versa)
+      - None if no match
+    """
+    _reload_if_changed()
+    q = query.strip().lower()
+    if not q:
+        return None
+
+    best = None
+    best_confidence = None
+
+    for entry in _entries:
+        # Exact match on name
+        if q == entry['name'].lower():
+            return {**entry, 'confidence': 'exact'}
+
+        # Exact match on any alias
+        if q in entry['aliases']:
+            return {**entry, 'confidence': 'exact'}
+
+        # Partial: query is substring of name/alias, or name/alias is substring of query
+        name_lower = entry['name'].lower()
+        if q in name_lower or name_lower in q:
+            if best is None:
+                best = entry
+                best_confidence = 'partial'
+            continue
+
+        for alias in entry['aliases']:
+            if q in alias or alias in q:
+                if best is None:
+                    best = entry
+                    best_confidence = 'partial'
+                break
+
+    if best is not None:
+        return {**best, 'confidence': best_confidence}
+
+    return None
+
+
+def list_all():
+    """Return all address book entries."""
+    _reload_if_changed()
+    return list(_entries)