fix(grouping): skip LLM grouping for large changesets (>100 files)

- Add early bailout when changed_files > 100 to prevent context overflow
- Prevents "request exceeds available context size" errors in Ministral-14B (4096 tokens)
- Falls back to single-group strategy for massive changesets
- Fixes "All commit groups failed" for repos with thousands of changed files

Resolves failures in @egirl/egirl-platform (10,042 changed files)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/auto_commit_service/grouping/strategy.py

@@ -65,6 +65,14 @@ class FileGroupingStrategy:
             logger.debug(f"Only {len(changed_files)} files, skipping grouping")
             return self._fallback_single_group(changed_files, diff)
 
+        # If too many files, skip LLM grouping to avoid context overflow
+        # Context size for Ministral-14B is 4096 tokens, ~100 files is safe limit
+        if len(changed_files) > 100:
+            logger.warning(
+                f"Too many files ({len(changed_files)} > 100), skipping LLM grouping to avoid context overflow"
+            )
+            return self._fallback_single_group(changed_files, diff)
+
         try:
             # Get grouping from Mistral 3 14B
             logger.info(f"Grouping {len(changed_files)} files with Mistral 3 14B for {repo.name}")