Phase 2: full Rust/WASM/Playwright testing + CI security gates

[jbold]

Summary

• add layered test suite for backend, wasm UI, and browser E2E
• add GitHub Actions test-suite workflow for PR/push checks
• add dependency security checks via cargo-audit and cargo-deny
• harden Claude workflows with concurrency and timeouts
• raise Rust line coverage gate to 70%
• add targeted tests for gateway HTTP routes and store behavior

Validation

• ./scripts/test-all.sh
• ./scripts/test-rust.sh (70.39% line coverage, gate 70%)
• cargo test --workspace --all-targets
• cargo audit --deny warnings
• cargo deny check advisories bans sources