chore(release): prepare v0.2.0

[rendyuwu]

What

Release prep for v0.2.0: the version is 0.2.0 everywhere it is set, and
CHANGELOG.md holds the dated [0.2.0] section in place of [Unreleased]
and [0.1.1].

Why

v0.2.0 ships the two changes merged into dev since v0.1.1:

• feat(extension): open the popup from the inline picker's more-logins row #21 the inline picker's more-logins row opens the Subclave popup
• fix(vault): let the join form follow the window and accept a blank Region #23 the join form follows the window and accepts a blank S3 Region

How

• Version 0.1.1 to 0.2.0 in package.json, extension/package.json, both
  extension manifests, src-tauri/tauri.conf.json, src-tauri/Cargo.toml,
  src-tauri/subclave-proxy/Cargo.toml, the two workspace entries in
  src-tauri/Cargo.lock (cargo update --workspace, no dependency moved),
  and the Version row in SUBCLAVE.md.
• CHANGELOG.md: ## [Unreleased] becomes ## [0.2.0] - 06-10-2026 with its
  entries unchanged, and the 0.1.1 section goes; it lives on in its GitHub
  Release.
• A minor bump: feat(extension): open the popup from the inline picker's more-logins row #21 is a feat and adds a request to the extension's
  protocol with the service worker (inline-open-popup).

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.

• cargo fmt --all -- --check,
  cargo check --workspace --all-targets --locked,
  cargo clippy --workspace --all-targets --locked -- -D warnings,
  cargo test --workspace --locked (325 passed).

• Both extension builds, lint:webext (0 errors) and
  pnpm --filter subclave-extension zip: the manifest.json inside
  subclave-chrome.zip and subclave-firefox.zip reads 0.2.0.

• node scripts/release-notes.mjs v0.2.0 prints the 0.2.0 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 code change, only version strings and docs.

Screenshots / GIFs

None. No UI change.

Notes for reviewer

• The CHANGELOG heading is dated 06-10-2026. A tag on another day needs that
  date moved first.
• Still untested from feat(extension): open the popup from the inline picker's more-logins row #21 and fix(vault): let the join form follow the window and accept a blank Region #23: the popup opening from the row in a headed
  Chrome 127 or later and in Firefox, the join screen in pnpm tauri:dev on
  WebKitGTK, and a join against a real R2 bucket with Region blank.