feat(ai): pre-fill qwen2.5:7b when Ollama is selected — 0.27.1

Selecting the Ollama provider pre-fills the model field with the suggested
qwen2.5:7b (fits an 8 GB GPU at Q4; grounding makes a 7B sufficient). Won't
overwrite a model the user already typed. Constant ai.OLLAMA_SUGGESTED_MODEL.

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

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to RigDoctor are recorded here. Format follows
 (`MAJOR.MINOR.PATCH`, pre-1.0). `__version__` and `pyproject.toml` must match the git
 release tag (so the auto-updater, D18, can compare versions).
 
+## [0.27.1] - 2026-05-22
+### Changed
+- AI assistant: selecting **Ollama** now pre-fills the model field with **`qwen2.5:7b`** (a
+  strong 7B that fits an 8 GB GPU; our grounding makes a 7B sufficient). It won't overwrite a
+  model you've already entered, and you can change it freely.
+
 ## [0.27.0] - 2026-05-22
 ### Added
 - **AI assistant (M14, D24)** — optional, **strictly opt-in, never automatic**. Explains your