Remove collision-era language from docs and code

- Updated FAQ.md, ADVANCED.md, TROUBLESHOOTING.md to explain hash IDs eliminate collisions
- Removed --resolve-collisions references from all documentation and examples
- Renamed handleCollisions() to detectUpdates() to reflect update semantics
- Updated test names: TestAutoImportWithCollision → TestAutoImportWithUpdate
- Clarified: with hash IDs, same-ID = update operation, not collision

Closes: bd-50a7, bd-b84f, bd-bda8, bd-650c, bd-3ef2, bd-c083, bd-85a6

examples/git-hooks/README.md

@@ -63,14 +63,16 @@ The hook is silent on success, fast (no git operations), and safe (fails commit
 After a git pull or merge, the hook runs:
 
 ```bash
-bd import -i .beads/issues.jsonl --resolve-collisions
+bd import -i .beads/issues.jsonl
 ```
 
 This ensures your local database reflects the merged state. The hook:
 - Only runs if `.beads/issues.jsonl` exists
-- Automatically resolves ID collisions from branch merges
+- Imports any new issues or updates from the merge
 - Warns on failure but doesn't block the merge
 
+**Note:** With hash-based IDs (v0.20.1+), ID collisions don't occur - different issues get different hash IDs.
+
 ## Compatibility
 
 - **Auto-sync**: Works alongside bd's automatic 5-second debounce