port build_host_files.py to Go, simplify Hermes MCP, cutover final

- cmd/hermes/main.go: removed redundant /mcp endpoint — Hermes gateway now
  serves only /query + /healthz. MCP goes direct to API (:8090/mcp).
- cmd/oikos/build_hosts.go: Go port of mcp/build_host_files.py as
  'oikos build-hosts'. Reads inventory.yaml, writes hosts/*.yaml.
- cmd/oikos/main.go: added build-hosts role.
- docker-compose.yml: hermes service simplified.
- apps/105: all 6 Oikos services stopped + disabled (confirmed inactive).
- Watchdog cron installed, API stop/restart verified.
- Infisical bootstrap pending (image pull timeout — retry separately).

Remaining:
- Port bin/homelab CLI to Go (separate plan — large surface)
- Caddy DNS push (needs dtoro/caddy-conf repo access)
- Rollback drill

hosts/mac-mini.yaml

@@ -1,24 +1,24 @@
-# Generated by mcp/build_host_files.py from inventory.yaml.
-# Do NOT edit by hand — your changes will be overwritten.
-# Source of truth: ../inventory.yaml
-name: mac-mini
+# Generated by oikos build-hosts from inventory.yaml.
+# Do NOT edit by hand.
+
+age_pubkey: age1z62ff2ak9zj5ctcvaxwyyhedwjvlwgm2dkn9nk3wrwk8fkavcpmsqwc2vs
 kind: workstation
-os: macos
-role: dev
-state: active
 lan_ip: 192.168.178.182
+mcp_endpoint: https://mcp.hubris.network/mcp
 mesh:
   netbird:
     fqdn: mac-mini-234-17.netbird.selfhosted
 mesh_globals:
-  primary: netbird
   accepted:
-  - netbird
-  - tailscale
+    - netbird
+    - tailscale
+  primary: netbird
+name: mac-mini
+notes:
+  - Only macOS in the fleet. Bootstrap uses launchd.
+os: macos
+role: dev
+secrets_issuance_endpoint: https://secrets.hubris.network/issue
 ssh:
   user: dtoro
-notes:
-- Only macOS in the fleet. Bootstrap uses launchd.
-age_pubkey: age1z62ff2ak9zj5ctcvaxwyyhedwjvlwgm2dkn9nk3wrwk8fkavcpmsqwc2vs
-mcp_endpoint: https://mcp.hubris.network/mcp
-secrets_issuance_endpoint: https://secrets.hubris.network/issue
+state: active