docs(orchestrator): close out IUV-M01 — mark tasks done, append session 2

Mark all six IUV-01 subtasks as done in docs/TASKS.md with merge commit
pointers, update MISSION-MANIFEST phase to Execution, and append
Session 2 to the install-ux-v2 scratchpad covering the M01 delivery:
PRs #440/#441/#442 merged, mosaic-v0.0.26 tagged and published to the
Gitea npm registry, plus the tsconfig/eslint cross-contamination
learning from the mid-delivery publish pipeline failure.

Refs #436

docs/MISSION-MANIFEST.md

@@ -7,7 +7,7 @@
 
 **ID:** install-ux-v2-20260405
 **Statement:** The install-ux-hardening mission shipped the plumbing (uninstall, masked password, hooks consent, unified flow, headless path), but the first real end-to-end run surfaced a critical regression and a collection of UX failings that make the wizard feel neither quick nor intelligent. This mission closes the bootstrap regression as a hotfix, then rethinks the first-run experience around a provider-first, intent-driven flow with a drill-down main menu and a genuinely fast quick-start.
-**Phase:** Planning
+**Phase:** Execution
 **Current Milestone:** IUV-M02
 **Progress:** 1 / 3 milestones
 **Status:** active