Gadfly: agentic adversarial PR reviewer (initial extraction)

Standalone, Docker-packaged extraction of the agentic PR reviewer that runs in
Gitea Actions: reads the checked-out repo with read-only tools (read_file/grep/
find_files/get_diff), verifies findings before reporting, two-pass review +
adversarial recheck, posts one labeled comment per model. Advisory only.

- cmd/gadfly: reviewer binary (majordomo + Ollama Cloud), zero deps beyond stdlib + majordomo
- entrypoint.sh: container brains — trigger gating, PR clone, model loop (logic out of YAML)
- Dockerfile: multi-stage; build-time module token never reaches the final image
- .gitea/workflows/build-image.yml: tag v* → build & push image
- examples/: ~15-line consumer stub
- system prompt genericized + hardened to re-derive constants/formulas (semantic bugs)

Vibe-coded with Claude Code; see README disclosure. Advisory, never blocks merge.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Steve Dudenhoeffer
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.