chore(release): prepare v0.1.0

[rendyuwu]

What

Release prep for v0.1.0: the live-site autofill checklist is gone, the
CHANGELOG section is dated, CONTRIBUTING's CI list is complete, and the
spin buttons on the two Settings > Security number fields are hidden.

Why

Closes #10.

The checklist in extension/test/sites.md made every release tag wait on a
15-minute live-site run, a hand check of the sites it reported blocked, and
two real-app sign-ins. Subclave has one user, so that is more process than it
needs: an autofill bug gets fixed when it shows up.

How

• Checklist: sites.md, sites.spec.ts (which read its Sites table),
  sites.config.ts and the test:sites script are deleted, along with the
  spec's testIgnore entries in extension/test/playwright.config.ts, the
  "Before the tag" step and the CI carve-out in SUBCLAVE.md. Nothing else
  used the spec's helpers, so no support code goes with it. The specs CI runs
  are unchanged.
• CHANGELOG.md: [0.1.0] is dated 03-10-2026. No Fixed lines for Settings > Security: the number fields' spin buttons clash with the theme #10 or
  fix(sync): add the conditional-write switch to the join screen #11, since neither fix touches a released version.
• CONTRIBUTING.md: the CI list gains pnpm typecheck:extension, which the
  frontend job runs between tsc --noEmit and pnpm build.
• Spin buttons (NumberRow in src/settings/sections/SecuritySection.tsx):
  the input gets [appearance:textfield] plus appearance-none on
  ::-webkit-inner-spin-button and ::-webkit-outer-spin-button. Tailwind v4
  has no textfield utility, so it is an arbitrary property. No -moz- rule:
  no Tauri webview is Gecko. The field stays type="number", so min/max,
  the spinbutton role and ArrowUp/ArrowDown stepping are unchanged, and
  commit still clamps to 0..=max. Nothing replaces the buttons.

Testing

• pnpm run lint:imports, pnpm run typecheck:scripts,
  pnpm run format:check, pnpm run verify (17/17),
  pnpm exec tsc --noEmit, pnpm run typecheck:extension, pnpm build.

• pnpm --filter subclave-extension test: 83 tests in 5 files, all green.

• The built CSS carries all three rules:
  ::-webkit-inner-spin-button{-webkit-appearance:none;appearance:none}, the
  same for ::-webkit-outer-spin-button, and
  appearance:textfield.

• Chromium (Playwright), with the built CSS and the field focused and hovered:
  a control input without the new classes shows the up/down arrows, and the
  patched one shows only its value.

• WebKitGTK's MiniBrowser under Xvfb rendered a black window every time, so
  WebKit is not tested.

• node scripts/release-notes.mjs v0.1.0 prints the 0.1.0 section and the
  macOS footer.

• pnpm exec tsc --noEmit clean

• Manual smoke-test of the affected feature

• (If you touched src-tauri/) cargo check clean

• (If UI) tested in pnpm tauri:dev (isolated dev data dir)

No changes under src-tauri/. Not tested in pnpm tauri:dev yet, nor in the
app on macOS (WKWebView) or Windows (WebView2).

Screenshots / GIFs

None attached. The only visual change is that the two fields lose their spin
buttons.

Notes for reviewer

• The checklist, its runner and the v0.1.0 run record (PR feat: M5 import, backup, release docs and the autofill checklist #8 at d38e1fb:
  42 yes, 1 no, 7 blocked) stay in history at d814683.