Fix dead code and uninstall regression in hook installer

- Remove unused _entry_matches_command function (dead code never called)
- Fix _strip_command_from_matcher_entry to preserve entries that don't
  contain the target command (previously entries with empty hooks arrays
  were silently dropped even if unrelated to primer)

Author: cursoragent

src/primer/hook/installer.py

@@ -180,24 +180,6 @@ def _install_claude(settings: dict, config: AgentHookConfig) -> bool:
     return already_end and already_compact
 
 
-def _entry_matches_command(entry: object, command: str) -> bool:
-    """True if a hook list entry (any supported format) references `command`."""
-    if isinstance(entry, str):
-        return entry == command
-    if not isinstance(entry, dict):
-        return False
-    # Legacy flat format
-    if entry.get("command") == command:
-        return True
-    # Matcher-wrapped format — entry matches if any inner hook targets the command
-    inner_hooks = entry.get("hooks", [])
-    if isinstance(inner_hooks, list):
-        for inner in inner_hooks:
-            if isinstance(inner, dict) and inner.get("command") == command:
-                return True
-    return False
-
-
 def _strip_command_from_matcher_entry(entry: dict, command: str) -> dict | None:
     """Remove the command from a matcher-wrapped entry, returning a cleaned
     entry or None if no inner hooks remain."""
@@ -207,6 +189,8 @@ def _strip_command_from_matcher_entry(entry: dict, command: str) -> dict | None:
     remaining = [
         h for h in inner_hooks if not (isinstance(h, dict) and h.get("command") == command)
     ]
+    if len(remaining) == len(inner_hooks):
+        return entry
     if not remaining:
         return None
     cleaned = dict(entry)