Bump Ruby WASM patch version

Bump Ruby patch version for WASM build with cascading updates

Coordinated Ruby patch bumps in Rails+WASM projects where version changes cascade across build config, Rust toolchain, and CI cache invalidation.

• · New Ruby version (e.g., 4.0.6)
• · Current .ruby-version, .wasi-vfs-version, .rust-version

• · Updated .ruby-version, .wasi-vfs-version (if needed)
• · Updated .rust-version (if wasi-vfs changed)
• · Updated lib/tasks/wasmify_patches.rake (tarball URL)
• · Updated docs/wasm-build-notes.md (reference)
• · Git commit with message "⬆️ Ruby <version>"

• · git (branching, commit)
• · bin/rails wasmify:build (local WASM build)
• · bin/rails wasmify:pack (local WASM pack)
• · npm run dev (local PWA test)

• · Ruby on Rails project with WASM build setup
• · wasmify_patches.rake exists
• · CI/Deploy using cache keys on .ruby-version

• · wasmify:build fails → WASM build pipeline broken
• · Cache invalidation causes full rebuild on next CI run
• · wasi-vfs version mismatch → Rust toolchain incompatibility
• · PWA local test fails → new Ruby version incompatible

• · Explicit verification step: bin/rails wasmify:build && pack
• · Local browser test before commit (real-world validation)
• · Documents cache key invalidation behavior
• · Covers optional .wasi-vfs and .rust-version updates only if needed