Tune-Up: persistent one-tap run-all dashboard (deferred from 0.7.2)

[caezium]

A first cut of a one-tap Tune-Up run-all shipped on `feat/ui-followups-2026-06-14` and was reverted before 0.7.2 — it was too thin. Tracking the real design here.

Problems with the first cut

• State didn't persist. Closing the Tune-Up sheet and reopening it reset everything — spinners/progress gone, run state lost. It must survive navigation and ideally app relaunch.
• It was a popup sheet. It should be its own screen/pane, not a modal that loses context.
• It only sequenced Clean + Optimize. It should be a proper "review everything, then act" surface.

Desired design

A persistent Tune-Up pane that, on entry, auto-runs the read-only/preview scans and flags what's worth reviewing, then lets the user act:

• Apps to uninstall — surface stale/large apps (last-used + size) for review.
• App updates — apps with updates available (Sparkle / App Store / Electron) + Homebrew outdated.
• Startup items to review — new/again-enabled login items & launch agents worth a look.
• Big disk users — top space hogs (drive from `mo analyze`) for review.
• Cleanable junk — the Clean dry-run total.
• Maintenance — Optimize tasks.

Then a one-tap "run the safe set" that executes the chosen items, with:

• Persisted status + progress across pane switches and relaunch (not a transient sheet).
• Expanding section cards → done summary.
• Conservative defaults + per-item opt-out + a visible pre-run plan.
• Honest auth handling (today each elevated step prompts separately; pooling needs the backlogged privileged helper).

Notes

• This is the "Smart Care"-style hub from `plans/ui-followups-2026-06-14.md` (PR-E), reworked from sheet → persistent pane with auto-flagged reviews.
• Reuse existing engines/flows (Clean/Optimize/Updates/Startup/Analyze) — no new process paths.