fix(activity-log): dashboard section reconciliation + activity column alignment

- dashboard full re-render now reconciles sections (only replaces changed ones) instead of wholesale .dashboard-dynamic innerHTML swap -> editing an entity no longer jumps the whole dashboard
- Recent Activity widget live DOM + perf strip preserved across re-renders; widget skips re-fetch when already populated (no flash)
- sweep stray non-section nodes so empty->populated doesn't leave an orphan 'no targets' banner (review-caught regression)
- Activity list rows use a CSS grid (fixed badge/actor columns) so message column aligns consistently across rows

plans/activity-log/PLAN.md

@@ -113,6 +113,9 @@ is an on-demand CSV/JSON **export** (no separate backup subsystem).
 | Manual test | Recent Activity widget missing from Customize Dashboard | 🟡 Warning | resolved — registered as a first-class dashboard section (show/hide/reorder; pre-existing layouts preserved) |
 | Manual test | Activity widget live event rebuilt the whole dashboard | 🟡 Warning (perf) | resolved — surgical list update; single listener with teardown |
 | Manual test | Relative-time labels static (never tick) | 🟡 Warning | resolved — shared `ensureRelativeTimeTicker` (single 30s interval, visibility-aware) |
+| Manual test | Dashboard fully rebuilt/jumped on entity edits (pre-existing `forceFullRender` wholesale innerHTML) | 🟡 Warning (UX) | resolved — section-level reconciliation (`_reconcileDynamicSections`): only changed sections replaced; widget live DOM + perf strip preserved |
+| Manual test | Activity list columns slightly misaligned | 🔵 Note | resolved — CSS grid with fixed badge/actor columns |
+| Manual test | Reconciler left orphan "no targets" node on empty→populated | 🟡 Warning (regression, caught in review) | resolved — sweep non-section top-level children |
 
 ## Final Review