refactor: improve worktree safety error message and simplify standalone review guidance

Inline CWD path into the main BLOCKED message and expand "CWD" abbreviation to
"working directory" for clarity. Simplify standalone stakeholder-review guidance by
removing reviewThreshold config reference and hardcoding HIGH+ threshold.

Author: cowwoc

client/src/main/java/io/github/cowwoc/cat/hooks/task/EnforceWorktreeSafetyBeforeMerge.java

@@ -55,11 +55,9 @@ public Result check(JsonNode toolInput, String sessionId, String cwd)
     if (isInsideWorktree(cwd))
     {
       String reason = """
-        BLOCKED: Shell CWD is inside a worktree that will be deleted during merge.
+        BLOCKED: Shell working directory (%s) is inside a worktree that will be deleted during merge.
 
-        Current CWD: %s
-
-        The merge subagent removes the worktree after merging. If the parent shell's CWD is inside
+        The merge subagent removes the worktree after merging. If the parent shell's working directory is inside
         the worktree when it is deleted, all subsequent Bash commands fail with exit code 1 until
         Claude Code is restarted.