Enable lint and format check jobs in CI (currently commented out)

[ScottMorris]

Context

The test.yml CI workflow has lint and format check steps commented out:

# - name: Lint Code
#   run: pnpm format:check

# - name: Rust Format Check
#   run: cargo fmt --all -- --check

# - name: Rust Clippy
#   run: cargo clippy --all-features -- -D warnings

tauri-plugins-workspace runs all of these as separate parallel jobs (fmt, clippy, lint-js, build-js) with GitHub Step Summary output. This is the org's most mature CI pattern.

Proposal

1. Uncomment and enable lint/format jobs
2. Split into parallel jobs matching the tauri-plugins-workspace pattern:
   • fmt — cargo fmt --all -- --check
   • clippy — cargo clippy --workspace --all-targets -- -D warnings
   • lint-js — pnpm format:check + pnpm lint (if available)
3. Add GitHub Step Summary output to each job

Acceptance Criteria

• Rust fmt and clippy checks enabled
• JS lint/format checks enabled
• Jobs run in parallel
• Step summaries added
• CI passes on current main