cloud/C8: LicenseSettings panel

[blueberrycongee]

What

Standalone settings panel for entering, viewing, and removing the Lumina Cloud license. Reads useLicenseStore directly — explicitly no dependency on AISettingsModal.tsx per the C8 spec, since that file is currently locked behind WIP.

Stacked on #220 (C4) because the panel binds to useLicenseStore. Stack chain: #217 (C1) → #218 (C2) → #220 (C4) → this PR.

Behavior by status

• idle: heading, helper copy, textarea, Verify button (disabled while empty or loading).
• loading: button label flips to "Verifying…", status line with role="status" mirrors it.
• invalid: role="alert" line — "Could not verify this license. Check the token and try again." The local verify path doesn't surface a granular reason; the online verify in §2.1 does, but that's C5/C9 territory.
• valid: <dl> with email / SKU / expiry / feature badges + a Remove license button. Click opens an inline role="alertdialog" confirmation — Remove calls clearLicense; Cancel just dismisses.

Tailwind for styling. Dark-mode classes throughout.

expires_at: null → "Lifetime"; non-null gets formatted as YYYY-MM-DD.

Acceptance criteria

• Paste license → calls useLicenseStore.setLicense → shows status (Verifying / Valid / Invalid + reason).
• Valid: shows email, SKU, expiry, features as quiet badges.
• "Remove license" button → confirmation → clearLicense.
• No dependency on AISettingsModal.tsx — verified by grep; only imports are useLicenseStore, LicensePayload type, and React.
• Tests cover the three status states (idle, valid, invalid). (plus loading via the disabled-button assertion in idle, and explicit Remove + Cancel flows.)
• Component renders without throwing in jsdom.

How I tested

• npm run typecheck: pass.
• npm test -- --run src/components/settings/LicenseSettings.test.tsx: 7/7 pass.
• Tests use vi.hoisted to mock verifyLicense / saveLicense / removeLicense / loadLicense from @/services/luminaCloud and exercise the store from the component side.

Touched files outside src/services/luminaCloud/

• New: src/components/settings/LicenseSettings.tsx + test — both inside the PRD §3 allow-list.
• cloud/TASKS.md — marked C8 [x] and appended Done-log entry.

Notes for Lead

• Inline alertdialog instead of window.confirm. Keeps it test-friendly and matches the rest of the app's component-level confirmation patterns.
• "Could not verify" copy is generic on purpose — the local Ed25519 path can't tell the user why (signature bad? malformed? wrong key?) without leaking implementation detail. The online verify in CONTRACT.md §2.1 returns a reason; if you want richer feedback later, hook §2.1 into the failure path.
• Mounted by C10 (Account tab). Until C10 lands, this component is unreachable in the app shell — that's fine; tests prove it works in isolation.

[blueberrycongee]

Closing — re-issued cleanly by integrator.