Initial implementation: AI code review bot for Gitea

- CLI binary with flag/env var configuration
- Gitea API client (PR metadata, diff, CI status, post review)
- OpenAI-compatible LLM client
- Structured review prompt with conventions support
- JSON response parser with validation
- Markdown review formatter for Gitea
- CI failure auto-detection (REQUEST_CHANGES)
- Dry-run mode for testing

README.md

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+# review-bot
+
+AI-powered code review bot for Gitea pull requests.
+
+## Overview
+
+`review-bot` fetches a PR's diff, title, description, and CI status from Gitea, sends it to an LLM via an OpenAI-compatible API, and posts a structured code review back to Gitea.
+
+## Usage
+
+```bash
+review-bot \
+  --gitea-url https://gitea.weiker.me \
+  --repo owner/name \
+  --pr 123 \
+  --reviewer-name "sonnet-review-bot" \
+  --reviewer-token "$(cat /path/to/token)" \
+  --llm-base-url "https://proxy.example.com/v1" \
+  --llm-api-key "key" \
+  --llm-model "anthropic--claude-4.6-sonnet" \
+  --conventions-file "CLAUDE.md"
+```
+
+All flags can also be set via environment variables:
+
+| Flag | Env Var |
+|------|---------|
+| `--gitea-url` | `GITEA_URL` |
+| `--repo` | `GITEA_REPO` |
+| `--pr` | `PR_NUMBER` |
+| `--reviewer-name` | `REVIEWER_NAME` |
+| `--reviewer-token` | `REVIEWER_TOKEN` |
+| `--llm-base-url` | `LLM_BASE_URL` |
+| `--llm-api-key` | `LLM_API_KEY` |
+| `--llm-model` | `LLM_MODEL` |
+| `--conventions-file` | `CONVENTIONS_FILE` |
+
+Use `--dry-run` to print the review to stdout without posting.
+
+## Build
+
+```bash
+go build -o review-bot ./cmd/review-bot
+```
+
+## Architecture
+
+- `cmd/review-bot/main.go` — CLI entry point
+- `gitea/client.go` — Gitea API interactions (fetch PR, diff, CI status, post review)
+- `llm/client.go` — OpenAI-compatible chat completion client
+- `review/prompt.go` — System/user prompt construction
+- `review/parser.go` — Parse LLM JSON response
+- `review/formatter.go` — Format markdown review body
+
+## Constraints
+
+- Pure Go stdlib, no external dependencies
+- No CGO