V2: WASI, -r flag, CI pipeline, examples & tests cleanup

WASI / wasm32 target support
- Auto-detect /usr/share/wasi-sysroot on Linux when target starts_with("wasm32")
- Skip -march/-mtune for wasm (clang rejects them)
- Apply -fno-exceptions -fno-c++-static-destructors -mllvm -wasm-enable-sjlj
  -D_WASI_EMULATED_SIGNAL to wasm builds (compile + std PCM, kept in sync)
- .wasm output extension in expectedOutputFor and link command
- EnableWasiBrowserRuntime(cfg): opt-in helper that drops index.html +
  runtime.js next to the .wasm; runtime.js reads window.CRAFTER_WASM_URL
  set in the templated index.html so a single shim handles any output name

-r run flag in the CLI: build then exec the artifact (host targets only;
  rejects libraries; auto .exe/.wasm extension handling)

CI pipeline (.forgejo/workflows/ci.yaml)
- Triggers: PR/push to master + manual dispatch
- Single arch-latest container job: install deps, bootstrap, self-rebuild,
  run tests, cross-compile mingw, package both archives, upload artifacts
- Rolling 'latest' release published only on push/dispatch to master

mingw cross-compile from Linux now works end-to-end:
- ExternalDependency cache key includes target so per-target glslang builds
  don't collide; CMAKE_BUILD_TYPE=Release pinned (otherwise glslang appends
  'd' to lib names and breaks linking); cross-compile cmake flags
  (CMAKE_SYSTEM_NAME=Windows, CMAKE_*_COMPILER_TARGET=...)
- project.cpp accepts --target=<triple>; Linux-only -Wl,--export-dynamic
  and -ldl are gated; mingw glslang skips the standalone exe (its libgcc_eh
  link pulls pthread which mingw doesn't link by default)
- mingw compile uses -femulated-tls so std::__once_callable etc reference
  the same emutls symbols libstdc++ provides
- mingw link auto-adds -lstdc++exp -lpthread

GetCrafterBuildHome() exposed from the Platform module; LoadProject (Linux
+ Windows) now both use it instead of duplicating the resolution.

Examples reorg: hello-world, library, with-module, wasi, tests — each with
its own README. Tests reorg: per-test directory with inner/ fixture, no
shared tests/fixtures/ tree. New Wasi test verifies .wasm magic bytes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/README.md

@@ -0,0 +1,12 @@
+# Examples
+
+Self-contained projects, ordered from simplest to most full-featured. Each example has its own README explaining what it shows.
+
+| Example | What it shows |
+|---|---|
+| [hello-world](hello-world/) | The minimum: `project.cpp` + `main.cpp` |
+| [with-module](with-module/) | Adding a C++ module interface |
+| [library](library/) | Library + executable, linked via `cfg.dependencies` |
+| [tests](tests/) | Auto-discovered tests + tests that link the parent library |
+
+Each example builds standalone: `cd examples/<name> && crafter-build`. Test examples: `crafter-build test`.