feat(builder): research, build and a worker for the AI builder

- research: searches SearXNG, reads the best pages through the reader, has the
  model list the server's variants, then checks every Docker image and Steam
  app it named for real before an admin sees it.
- build: first boot of the variant's images (skipping ones that need root),
  a draft by the model, then the draft deployed with the node-agent's
  BootTest like CI does; crashes, error lines and saves outside /server go
  back to the model, three boots at most.
- worker: polls the panel's builder queue (outbound only), runs research or
  build in a fresh clone, streams the output as the job log, and opens the
  result as a pull request from the bot account.
- Dockerfile.builder, a workflow publishing gbr-builder:latest, and
  BUILDER.md. Everything about where it runs comes from environment
  variables; deployment files live outside this public repo.

draft now keeps its conversation in a drafter, so build can send boot
failures back to the same model session. The boot-test runner comment no
longer names its VM.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

BUILDER.md

@@ -0,0 +1,61 @@
+# AI builder (gbrgames worker)
+
+The panel's **AI builder** (Admin → Games → AI Config Generator) is run by a worker we host ourselves.
+The panel only keeps a queue; every result is a pull request to this repo, which CI validates and
+boot-tests like any other.
+
+```
+Panel                                     Builder worker (gbrgames worker, Docker)
+─────                                     ─────────────────────────────────────────
+admin starts a job ──► queued    ◄─poll── research: web search + page reader + model
+progress / log / variants        ◄─post── build: first boot → draft → boot with the node-agent
+"Review draft PR"                         → branch draft/<id>-<job> + PR as the bot ──► CI (validate + boot test)
+```
+
+1. **Research** (`gbrgames research -name N`): searches the web, reads the best pages, and has the model list
+   the server's variants (edition, image or SteamCMD app, startup, ports). Every image and Steam app is
+   checked for real (`docker manifest inspect`, anonymous `steamcmd +app_info_print`) before the admin
+   sees it.
+2. The admin picks a variant in the panel.
+3. **Build** (`gbrgames build -name N -variant @v.json`): first boot of the image untouched (`first-boot`), a
+   draft by the model (`draft`, rules in `AUTHORING.md`), then the draft is deployed with the node-agent's
+   `BootTest`, the same check CI runs. Failures (crash, error lines, saves written outside `/server`) go
+   back to the model, three boots at most.
+4. The worker pushes `games/<id>/` to a branch and opens a pull request as the bot account. A draft that
+   validates but never booted still gets a PR, titled `WIP:`, with what's left listed. Nothing reaches
+   players until a person merges it and enables the game.
+
+The worker only connects out (to the panel, Gitea, the model and the search services).
+
+## Requirements
+
+A Docker host with the isolated `gbr-boottest` network (`RUNNER.md`, step 1), so servers booted by the
+builder can't reach private networks. Enough memory for the largest server it builds (~16 GB for ARK) and
+disk for SteamCMD downloads. The image `gbr-builder:latest` is published by
+`.gitea/workflows/builder-image.yml` whenever `cmd/` changes on main.
+
+## Configuration
+
+All through environment variables; nothing about where it runs lives in this repo.
+
+| Variable | What |
+| --- | --- |
+| `PANEL_URL` | The panel the worker takes jobs from |
+| `BUILDER_TOKEN` | Shared secret the panel checks on `/api/v1/builder/**` (same value in the panel's env) |
+| `GITEA_TOKEN` | The bot account's token (repository read/write on this repo): pushes draft branches, opens PRs |
+| `OLLAMA_URL` | Ollama for the model (or `MODEL_PROVIDER=gemini` with `GEMINI_API_KEY`) |
+| `SEARXNG_URL`, `READER_URL` | A SearXNG instance (JSON API) and a page-to-text reader (`READER_URL/<page url>`) |
+| `MODEL`, `POLL_INTERVAL`, `WORKER_NAME`, `WORK_DIR` | Optional: model name, poll interval (20s), name shown in the panel, work folder |
+
+## Running a build by hand
+
+On any machine with Docker and the `gbr-boottest` network, with `OLLAMA_URL`, `SEARXNG_URL` and
+`READER_URL` set:
+
+```bash
+go run ./cmd/gbrgames research -name Valheim -out research.json
+# pick a variant from research.json into v.json, then:
+go run ./cmd/gbrgames build -name Valheim -variant @v.json -out build.json
+```
+
+The draft lands in `games/<id>/`, first-boot reports in `firstboot-out/`.