test(notes): gate note persistence across versions

[yattdev]

$## Overview\n\nAdd hard compatibility gates for Notes persistence across published plugin versions and document the safe upgrade path.\n\n## Review first\n\n1. ui/persistence-compat.test.mjs — loads every released Notes bundle and verifies byte-exact task/workspace note preservation in upgrade and downgrade directions, permanent namespace coordinates, and zero deletes.\n2. integration/host_upgrade_preserves_user_state_test.go with scripts/test-host-upgrade-state.sh — overlays a focused test into Kandev’s real Service.Install package, proving both newer and older replacements do not call the user-state cleanup seam.\n3. server/manifest_test.go, CI/release workflow fetch-depth: 0, and the README lifecycle guidance — keep the contract and released history available to the gates.\n\n## Changes\n\n- add a UI persistence compatibility suite that replays every published Notes tag against the current bundle in both upgrade and downgrade directions\n- add a host lifecycle contract test plus runner script to assert version replacement never purges plugin user state\n- pin the released plugin id and user_state capability in server tests, wire the new checks into make test, and fetch full tag history in CI/release workflows\n- document in-place update/downgrade versus destructive uninstall/reinstall semantics in the README and annotate the manifest persistence contract\n\n## Verification\n\n- CI: 3 successful checks on 3e2e0aaebcbb94e334cc2cc0ced0b5717ff65eca\n- make test in a disposable sibling-host layout: server suite, 108 Node tests, and the real host lifecycle overlay contract\n- go vet ./server/..., formatting/diff checks, and make package-host; the packaged manifest retains id: "kandev-plugin-notes" and user_state: true\n- current-head focused historical matrix: node --test ui/persistence-compat.test.mjs (10/10)\n\n## Breaking Changes\n\nNone. Version replacement is safe; explicit uninstall/reinstall remains intentionally destructive.