feat(m14): AI assistant — explain diagnostics, opt-in (Ollama or Claude) — 0.27.0

New optional module (D24): explains the collected findings in plain language,
contacted ONLY on an explicit user action (never automatic).

- core/ai.py: provider chosen explicitly (no default) — ollama (local) or claude
  (Anthropic Messages API via stdlib urllib; key in keyring). Grounded prompt;
  HTTP error parsing; one-shot (no thinking/caching — snappy).
- core/ai_knowledge.py: curated reference KB (Xid/SMART/Proton/tunables),
  exact keyword/code match ("RAG-lite", no embeddings) injected into the prompt —
  lifts local models, sharpens Claude. No fine-tuning.
- config: ai_provider/ai_model/ai_endpoint + keyring-backed AI key (generalized
  the token keyring helpers).
- GUI: Settings → AI assistant (provider radios, model/endpoint/key, Save/Test);
  "Explain with AI" button on the diagnostic dialog (consent prompt for cloud).
- CLI: `rigdoctor ai status|test|explain`.
- Docs: D24, SPEC/MODULES/ROADMAP (Phase 7); tests for providers/grounding/parse.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "rigdoctor"
-version = "0.26.1"
+version = "0.27.0"
 description = "Modular hardware monitoring & crash diagnostics for Linux gamers."
 readme = "README.md"
 requires-python = ">=3.11"