VSCode extension: no hook fires when user rejects a tool permission prompt

When a tool permission prompt is denied in the VSCode extension, no hook event fires. This leaves any stateful hook-driven UI orphaned with no cleanup signal.

**Expected behavior:** A hook event fires after a tool permission is denied — either `PermissionDenied`, `PostToolUseFailure`, or `StopFailure` — so hooks can react and reset state.

**Actual behavior:** None of the following hooks fire on user rejection in VSCode: `PostToolUseFailure`, `PermissionDenied`, `StopFailure`, `Stop`. The session continues silently with no hook signal.

**Environment:** Claude Code VSCode extension (confirmed working in test: hooks fire normally for `SessionStart`, `SessionEnd`, `Stop`, `UserPromptSubmit`; none fire on tool rejection)

Start by tracing the VSCode extension's tool-permission rejection path and compare it with the existing hook events listed in the issue. Done means a user rejection emits one of PermissionDenied, PostToolUseFailure, or StopFailure, with coverage for the reported VSCode behavior.

Written by the indexing model from the issue text.