Add teabot daemon implementation

teabot watches Gitea repos and dispatches one-shot Claude Code sessions in
Docker containers to work issues and review PRs, acting as configurable bot
personalities.

Claude-Session: https://claude.ai/code/session_015ur3i7D2azsMAWTSVABApv

internal/config/example.go

@@ -0,0 +1,57 @@
+package config
+
+// Example is a fully-commented sample config written by `teabot config init`.
+const Example = `# teabot configuration
+# Location: $XDG_CONFIG_HOME/teabot/config.yaml (default ~/.config/teabot/config.yaml)
+
+# Base URL of the Gitea instance to watch.
+gitea_url: https://git.unkin.net
+
+# How often to poll each repo.
+poll_interval: 60s
+
+# Repositories to watch, in owner/name form.
+repos:
+  - unkin/teabot
+
+# Maximum number of Claude job containers running at once.
+max_concurrent: 2
+
+# Per-session wall-clock timeout.
+job_timeout: 30m
+
+# Container image each session runs in. The default already ships the Claude
+# CLI plus a Go/Node/Python/tea developer toolchain.
+job_image: git.unkin.net/unkin/agent-dev:latest
+
+# Home directory inside job_image (mount target for tea/claude config).
+container_home: /home/agent
+
+# Host directory holding Claude Code credentials (subscription auth). A private
+# copy is mounted into each container so token refreshes never touch this dir.
+claude_config_dir: ~/.claude
+
+# Optional: use an Anthropic API key / gateway instead of subscription auth.
+# When set these are injected as ANTHROPIC_API_KEY / ANTHROPIC_BASE_URL.
+# anthropic_api_key: ""
+# anthropic_base_url: ""
+
+# Optional: override the state directory (default ~/.local/state/teabot).
+# state_dir: ~/.local/state/teabot
+
+# Bot personalities. Each is a distinct Gitea account backed by its own tea
+# config file (create it with: tea logins add --name <bot> ...). teabot reads
+# the token + username from that file and mounts it into the container so tea
+# acts as this identity. Roles: implementer, reviewer, both.
+personalities:
+  - name: implementer
+    tea_config: ~/.config/teabot/tea-implementer.yml
+    role: implementer
+    git_name: Teabot Implementer
+    git_email: teabot-implementer@unkin.net
+  - name: reviewer
+    tea_config: ~/.config/teabot/tea-reviewer.yml
+    role: reviewer
+    git_name: Teabot Reviewer
+    git_email: teabot-reviewer@unkin.net
+`