[docs](trx-rs): consolidate documentation into docs/ wiki

Move scattered documentation into the docs/ submodule (GitHub wiki):
- OVERVIEW.md → docs/ARCHITECTURE.md
- SCHEDULER.md, aidocs/CONFIGURATION.md, aidocs/AUTH.md → docs/MANUAL.md
- OPTIMIZATION.md → docs/OPTIMIZATION_GUIDELINES.md
- RECORDER.md → docs/NEXT.md
- Remove aidocs/ (content migrated or obsolete)
- Update README.md documentation links

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

README.md

@@ -173,7 +173,8 @@ See [`examples/trx-plugin-example/README.md`](examples/trx-plugin-example/README
 
 ## Documentation
 
-- [`OVERVIEW.md`](OVERVIEW.md): architecture and design overview
+- [User Manual](docs/MANUAL.md): configuration, features, and usage
+- [Architecture](docs/ARCHITECTURE.md): system design, crate layout, data flow, and internals
 - [`CONTRIBUTING.md`](CONTRIBUTING.md): contribution and commit rules
 
 ## Project Status