Add Iroh relay mode config

docs/roadmap.md

@@ -74,14 +74,20 @@ geth-to-geth connections without granting trust from discovery alone.
   - Endpoint identity is bound to agent/node identity in local metadata.
   - Restarting the daemon preserves higher-level node identity.
 
-- `[ ]` Relay policy and configuration.
+- `[x]` Built-in relay policy and configuration.
   Acceptance criteria:
-  - Config can select disabled, default Iroh relays, staging relays, and future
-    custom relay maps.
+  - Config can select disabled, default Iroh relays, and staging relays.
   - The intended product default uses relays unless explicitly disabled.
   - `geth status --json` reports the selected relay mode.
   - Tests cover config parsing and endpoint builder relay-mode selection.
 
+- `[ ]` Custom relay maps.
+  Acceptance criteria:
+  - Config can define and select named custom relay maps.
+  - Invalid relay URLs fail config validation with clear errors.
+  - Status output identifies the selected custom relay map without exposing
+    unrelated config.
+
 - `[ ]` LAN mDNS discovery.
   Acceptance criteria:
   - The daemon can advertise and discover local geth peer cards over mDNS.