feat: improve AI commit experience and remove message length limits

- Remove 72-char limit on AI-generated commit messages (no more ... truncation)
- Add [Y/n] confirmation prompt when using local heuristics (no AI provider)
  - Default to Y (press Enter to accept)
  - Clearly warns user about local heuristics vs AI
  - Bypass with --yes flag for automation
- Enhanced transparency: users now know when AI is used vs local pattern matching
- Safer commits when API keys are not configured
- Bumped version to 0.6.6

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gims",
-  "version": "0.6.5",
+  "version": "0.6.6",
   "description": "Git Made Simple – AI‑powered git helper using Gemini / OpenAI",
   "author": "S41R4J",
   "license": "MIT",