Move config/test/models to daemon TCP protocol, TUI uses .env fallback

- Daemon: add handle-client-config inline handler for :config-get,
  :config-set, :config-list, :provider-test, :provider-models
- TUI cmd-config: write .env directly, send reload to daemon if connected
- TUI: /config test and /config models send TCP to daemon (fallback:
  daemon-not-running message)
- Add Test Provider and Discover Models to Ctrl+P daemon commands

org/channel-tui-state.org

@@ -333,6 +333,8 @@ Semantic keys (all presets define these):
   '((:title "Status — Daemon health info"          :value (:action :status))
     (:title "Stats — Daemon statistics"              :value (:action :stats))
     (:title "Ping — Daemon reachability"             :value (:action :ping))
+    (:title "Test Provider — Check connection"      :value (:action :provider-test))
+    (:title "Discover Models — List available"       :value (:action :provider-models))
     (:title "Memory Snapshot — Capture state"        :value (:action :memory-snapshot))
     (:title "Memory Rebuild — Rebuild indices"       :value (:action :memory-rebuild))
     (:title "Memory Compact — Optimize storage"      :value (:action :memory-compact))