Fix #264 and #262: Remove stale --resolve-collisions references

- Update examples/git-hooks README to use 'bd hooks install' instead of non-existent install.sh
- Fix post-merge hook error message to not suggest --resolve-collisions flag (removed in v0.20)
- Clean up all doc references to --resolve-collisions (flag removed, hash IDs prevent collisions)

Fixes #264 (git hooks installer missing)
Fixes #262 (misleading error message)

Amp-Thread-ID: https://ampcode.com/threads/T-c9f0e4cb-fba2-4db2-a3d5-36dc1892be9d
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/init.go

@@ -699,7 +699,7 @@ fi
 # Import the updated JSONL
 if ! bd import -i .beads/issues.jsonl >/dev/null 2>&1; then
     echo "Warning: Failed to import bd changes after merge" >&2
-    echo "Run 'bd import -i .beads/issues.jsonl' manually" >&2
+    echo "Run 'bd import -i .beads/issues.jsonl' manually to see the error" >&2
 fi
 
 exit 0
@@ -734,7 +734,7 @@ fi
 # to ensure immediate sync after merge
 if ! bd import -i .beads/issues.jsonl >/dev/null 2>&1; then
     echo "Warning: Failed to import bd changes after merge" >&2
-    echo "Run 'bd import -i .beads/issues.jsonl' manually" >&2
+    echo "Run 'bd import -i .beads/issues.jsonl' manually to see the error" >&2
     # Don't fail the merge, just warn
 fi