docs: rewrite PLAN.md and update CODEBASE.md, README.md

- Full rewrite of PLAN.md to reflect current architecture (27 REST + 3 WS endpoints,
  embedded frontend, automation, scheduler, health check, GoReleaser CI)
- Added health.go, mods.go, scheduler.go, robfig/cron dep to CODEBASE.md
- Added Gitea Actions CI/CD section to CODEBASE.md
- Added conventional commits to code style section
- Added missing API routes and embed/ to README.md

README.md

@@ -117,11 +117,16 @@ REST API at `/api/*` and WebSocket endpoints at `/ws/*`. Key routes:
 | `GET/POST/PUT/DELETE` | `/api/configs` | CRUD for `.cfg` files |
 | `GET/POST/PUT/DELETE` | `/api/modlists` | CRUD for modlists |
 | `POST` | `/api/modlists/import` | Import HTML workshop list |
+| `GET` | `/api/modlists/:id/export` | Export to downloadable HTML preset |
 | `GET` | `/api/modlists/:id/check` | Check mod download status |
 | `POST` | `/api/modlists/:id/download-missing\|update-all` | Bulk workshop operations |
 | `POST` | `/api/server/steamcmd/update-game\|download-mod` | SteamCMD operations |
+| `GET` | `/api/mods` | List installed mods (workshop + local) with usage info |
+| `DELETE` | `/api/mods` | Delete a mod by path |
+| `POST` | `/api/mods/cleanup` | Bulk-delete all orphaned mods |
 | `GET` | `/api/server/logs` | List log files |
 | `GET` | `/api/server/paths` | Show server file paths |
+| `GET` | `/api/server/health` | Comprehensive health check |
 | `WS` | `/ws/server/logs\|rpt\|steamcmd/logs` | Live log streaming |
 
 ## Project Structure
@@ -129,6 +134,7 @@ REST API at `/api/*` and WebSocket endpoints at `/ws/*`. Key routes:
 ```
 backend/
   cmd/server/          Entry point
+  embed/               Embedded frontend assets (//go:embed)
   internal/
     api/               HTTP handlers and routes
     models/            Data types