[Capture] Clear uncommitted label draft after successful submit

[Chris0Jeky]

Closes #2057

Summary

• clear the transient label input when the parent confirms a successful Paper capture reset
• keep the uncommitted input intact until that success confirmation
• cover both states in the focused composer spec

Verification

• npm test -- --maxWorkers=2 src/tests/views/paper/inbox/PaperCaptureComposer.spec.ts
• npm run typecheck
• npx eslint src/views/paper/inbox/PaperCaptureComposer.vue src/tests/views/paper/inbox/PaperCaptureComposer.spec.ts
• git diff --check

ESLint reports one existing vuejs-accessibility/label-has-for warning at PaperCaptureComposer.vue:261; no errors.

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[Chris0Jeky]

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[Chris0Jeky]

Review gate (Codex credits exhausted, SC-9): one fresh-context reviewer confirmed resetDraft fires only after captureStore.createItem resolves (PaperInboxView.vue:191) or on explicit discard, never on failure or board-scope change; the in-flight race is closed by the disabled label input while submitting; the spec drives the real exposed resetDraft. Frontend Unit passed at this head in CI. Verdict SHIP. MEDIUM follow-up (submit does not flush an uncommitted label, so the clear is lossy) plus two LOW residuals tracked in #2490. Merging.