feat: peer access config, DNS fix, real routing table, reinstall notifications

Peer creation/edit form now configures:
- Tunnel mode: full (0.0.0.0/0) or split (PIC only)
- Per-service access toggles (calendar, files, mail, webdav)
- Peer-to-peer communication toggle
- Optional calendar account creation
- Access capability badges in peer list

Bug fixes:
- DNS in client configs was 8.8.8.8 / 172.20.0.2 — now 172.20.0.3 (CoreDNS)
  This was why .cell domains didn't resolve on connected VPN peers
- get_peer_config API uses stored internet_access to set AllowedIPs
- New PUT /api/peers/<name> endpoint with config_changed detection
- POST /api/peers/<name>/clear-reinstall clears reinstall flag after download
- Routing page reads real host routes via /proc/1/net/route (pid: host)

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

api/peer_registry.py

@@ -266,6 +266,27 @@ class PeerRegistry(BaseServiceManager):
             self.logger.error(f"Error removing peer {name}: {e}")
             return False
 
+    def update_peer(self, name: str, fields: Dict[str, Any]) -> bool:
+        """Update arbitrary fields on a peer."""
+        try:
+            with self.lock:
+                for peer in self.peers:
+                    if peer.get('peer') == name:
+                        peer.update(fields)
+                        peer['updated_at'] = datetime.utcnow().isoformat()
+                        self._save_peers()
+                        self.logger.info(f"Updated peer {name}: {list(fields.keys())}")
+                        return True
+                self.logger.warning(f"Peer {name} not found for update")
+                return False
+        except Exception as e:
+            self.logger.error(f"Error updating peer {name}: {e}")
+            return False
+
+    def clear_reinstall_flag(self, name: str) -> bool:
+        """Clear the config_needs_reinstall flag after user downloads new config."""
+        return self.update_peer(name, {'config_needs_reinstall': False})
+
     def update_peer_ip(self, name: str, new_ip: str) -> bool:
         """Update peer IP address"""
         try: