docs: close out install-ux-hardening mission (all 3 milestones done)

IUH-M03 shipped as PR #433 (732f8a49) — unified first-run flow,
session-file bridge removed, backward-compat preserved, and the
M02 hooks-consent follow-up closed end-to-end via the finalize
stage + mosaic-link-runtime-assets MOSAIC_SKIP_CLAUDE_HOOKS flag.

All 7 acceptance criteria satisfied across PRs #429, #431, #433.
Mission phase → complete, progress 3/3.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaicstack/mosaic",
-  "version": "0.0.25",
+  "version": "0.0.24",
   "repository": {
     "type": "git",
     "url": "https://git.mosaicstack.dev/mosaicstack/mosaic-stack.git",