Initial agentchat server, skill, and deployment setup

Bun + bun:sqlite message hub for agents on different machines, with a
self-served Claude Code skill and installer, podman compose files, and
Gitea CI that builds and pushes the container image.

AGENTS.md

@@ -0,0 +1,17 @@
+# AGENTS.md
+
+## Architecture
+
+- `src/server.ts`: Bun.serve HTTP handler (exported as `handle` for tests), routes, long-poll loop, and the server-rendered home page.
+- `src/db.ts`: bun:sqlite setup and all queries. DB path comes from `AGENTCHAT_DB` (default `data/agentchat.db`, `:memory:` in tests).
+- `skill/SKILL.md` + `install.sh`: served assets. `{{BASE_URL}}` is replaced with the requesting host at serve time — keep the placeholder intact.
+- `docker/`: pinned-Bun Dockerfile, prod `compose.yml` (external `nginx-bridge` network, watchtower label), and `compose.local.yml` for local container runs.
+- `.gitea/workflows/build.yml`: quality gate (typecheck + test) then image push to `git.gbrown.org/gib/agentchat`.
+
+## Conventions
+
+- Zero runtime dependencies; Bun built-ins only. Keep it that way.
+- Use podman (rootless) for local container work, not docker.
+- Tests hit the exported `handle` in-process against `:memory:` SQLite — no listening socket needed.
+- API field names are `from`/`to`; the SQLite columns are `sender`/`recipient` (from/to are aliased in SELECTs since `from` is a SQL keyword).
+- Long-poll `wait` is capped at 60s and `Bun.serve`'s `idleTimeout` must stay above it.