[iPeluwa]

ZCode desktop sessions do not run the shell wrappers, so Vibetime never sees them. This adds ZCode to the desktop hook lifecycle and includes the fixes from #122.

• Install, reconcile and remove hooks in ~/.zcode/cli/config.json alongside the existing desktop integrations.
• Map SessionStart to session start, and UserPromptSubmit, PostToolUse and Stop to activity. Sessions close through the inactivity reaper because ZCode provides no session-end event.
• Normalize sess_<uuid> IDs and ignore sub-agent IDs to prevent duplicate sessions.
• Preserve user-approved hooks when their commands match. A changed executable path creates a fresh hook requiring approval in ZCode again.
• Return without writing the config when nothing changed, preserving its exact bytes and modification time and avoiding a routine repair overwriting a toggle the user is saving.
• Preserve unrelated commands and matcher-group metadata when Vibetime shares a group with other hooks, including during stale-command replacement and uninstall.
• Leave invalid JSON and unsupported config shapes untouched. Document restart and Settings → Hooks approval without enabling hooks automatically.

Validation: the complete local suite passes 160/160. Tests cover merging, idempotency, saved approval, replacement, removal, invalid/unsupported configuration, fresh configuration, ID normalization and sub-agent exclusion. Added regressions verify no write on a matching enabled config and preservation of mixed groups; all three new regressions fail against the previous PR head.

The earlier macOS live verification is recorded in #122. This review reruns automated tests and does not claim a fresh ZCode desktop check. Windows and Linux desktop acceptance remain unverified.

Combined validation: all three revised branches merge cleanly in the order below and pass 192/192 local tests together.

Merge order: 1. #127 (storage) → 2. #129 (delivery) → 3. #128 (this PR). This replaces the closed #122.

[iamnotstatic]

Checked this against the #122 notes: the no-op repair now leaves the file alone (bytes and mtime), and odd shapes are left untouched instead of throwing. The mixed group handling is a nice addition. Only nit: a valid file with an unexpected shape says "not valid JSON", which might confuse someone. Good to go once #129 is in.