feat(compiler): add built-in ASC, Go, and Rust language plugins

[anistark]

The Examples CI workflow was failing on 13 of 14 jobs due to several compounding issues. This commit addresses them all.

New built-in language plugins so wasmrun compile works without requiring external plugin installation:

• AscPlugin: detects asconfig.json or assemblyscript in package.json, runs npm run build, copies output .wasm
• GoPlugin: detects go.mod/.go files, runs tinygo build -target wasi
• RustPlugin: detects Cargo.toml, runs cargo build --target wasm32-unknown-unknown + wasm-bindgen

Additional bug fixes driving the CI failures:

• detect.rs: ASC detection now checks asconfig.json first (neither asc-hello nor web-asc had the "asc" string the old check required); broadened to match assemblyscript in package.json; removed plugin-URL strings from Go/Rust tool lists
• metadata.rs: infer_plugin_details now recognises "waspy" and "python", returning ["py"] extensions so the waspy plugin's can_handle_project matches Python projects correctly

CI workflow changes (examples.yml):

• Remove nodejs-express-api (OS-mode example, not a WASM compile target)
• Add TinyGo install steps (Linux tarball, Windows zip) for go-hello
• Split waspy plugin install into OS-specific steps using the correct binary name (wasmrun.exe on Windows)
• Add emscripten dir to GITHUB_PATH so bash subprocesses spawned by make can find emcc on Windows (fixes c-hello Windows)
• Replace [ -f *.wasm ] glob check with find-based count
• Increase compile timeout to 120s/5min for Rust builds