Add contacts/phone book system with per-user scoping

New files:
- lib/auth.py: Authentik forward-auth helpers (get_user_id, @require_auth)
- lib/contacts.py: ContactsDB with CRUD, soft delete, restore, purge, find_nearby
- lib/contacts_api.py: Flask Blueprint with 9 API endpoints at /api/contacts
- templates/knowledge/deleted_contacts.html: Dashboard recovery page

Modified:
- lib/api.py: Register contacts_bp, add KNOWLEDGE_SUBNAV entry, /deleted-contacts route
- config/profiles: has_contacts feature flag (true for home, false for pi profiles)

Separate SQLite DB at data/contacts.db. Per-user isolation via X-Authentik-Username.
Home/Work labels enforced unique per user. Haversine proximity queries (75m default).

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

lib/api.py

@@ -63,6 +63,10 @@ app.request_class = _LargeZimRequest
 from .address_book_api import address_book_bp
 app.register_blueprint(address_book_bp)
 
+# ── Contacts Blueprint ──
+from .contacts_api import contacts_bp
+app.register_blueprint(contacts_bp)
+
 # ── Netsyms + Geocode Blueprints ──
 from .netsyms_api import netsyms_bp, geocode_bp
 app.register_blueprint(netsyms_bp)
@@ -78,6 +82,7 @@ KNOWLEDGE_SUBNAV = [
     {'href': '/upload', 'label': 'Upload'},
     {'href': '/web-ingest', 'label': 'Web Ingest'},
     {'href': '/failures', 'label': 'Failures'},
+    {'href': '/deleted-contacts', 'label': 'Deleted Contacts'},
 ]
 
 PEERTUBE_SUBNAV = [
@@ -323,6 +328,18 @@ def failures_page():
                            failures=failures)
 
 
+@app.route("/deleted-contacts")
+def deleted_contacts_page():
+    from .auth import get_user_id
+    from .contacts import ContactsDB
+    user_id = get_user_id() or "anonymous"
+    db = ContactsDB()
+    contacts = db.list_deleted(user_id)
+    return render_template("knowledge/deleted_contacts.html",
+                           domain="knowledge", subnav=KNOWLEDGE_SUBNAV, active_page="/deleted-contacts",
+                           contacts=contacts)
+
+
 @app.route('/peertube')
 def peertube_dashboard():
     return render_template('peertube/dashboard.html',