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/tests/README.md

@@ -0,0 +1,54 @@
+# tests
+
+Two ways to write tests, in one project.
+
+```sh
+cd examples/tests
+crafter-build test
+```
+
+Layout:
+
+```
+mylib/MyMath.cppm                  # the library being tested
+project.cpp                        # declares the library
+
+tests/Smoke/main.cpp               # zero-config test (no project.cpp)
+tests/UnitMyMath/main.cpp          # test that links MyMath and exercises it
+tests/UnitMyMath/project.cpp       # required for tests with deps
+```
+
+## Auto-discovery
+
+Each `tests/<Name>/` directory becomes a test. Three layers, escalate only as needed:
+
+1. **`tests/<Name>/main.cpp`** with no `project.cpp` — discovery synthesizes a Configuration. Top-level `*.cpp` files become implementations, `interfaces/*.cppm` become module interfaces. `Smoke` is this case.
+2. **`tests/<Name>/project.cpp`** — full control. Use this when you need defines, dependencies, or non-default targets. `UnitMyMath` is this case (it depends on `MyMath`).
+3. Folders starting with `_` or `.` are skipped (e.g. `tests/_shared/` for cross-test helpers).
+
+## Test conventions
+
+- Exit code `0` = pass, anything nonzero = fail, **`77` = skipped** (autoconf convention). Use `std::exit(77)` for runtime skips like "tool not on PATH".
+- Each test runs in its own subprocess; a segfault doesn't take down the runner.
+- Default timeout is 60 s (`crafter-build test --timeout=N` overrides).
+- Filter by name: `crafter-build test 'Unit*'`. List without running: `crafter-build test --list`.
+
+## Linking the parent project
+
+`UnitMyMath/project.cpp` shows how a test links the project's own library:
+
+```cpp
+cfg.dependencies = { ParentLib("MyMath") };
+```
+
+`ParentLib("name")` looks up a `Configuration*` in the parent project (the root project's own config + its dependency graph) by `Configuration::name`. The fixture's project.cpp can omit `cfg.path`, `cfg.name`, etc. — the discovery loop fills folder-derived defaults.
+
+## Cross-target test runs
+
+Tests parse `--target=...` from the project args you pass on the command line:
+
+```sh
+crafter-build test --target=x86_64-w64-mingw32 --runner=cmd:wine
+```
+
+`--runner=<spec>` overrides the per-target runner for this invocation. Useful specs: `local`, `cmd:<command>` (prefix-exec, e.g. `cmd:wine`, `cmd:qemu-aarch64`), `ssh:<host>[:<remoteDir>]`, `sshwin:<host>[:<remoteDir>]`. Or persist via env var: `CRAFTER_BUILD_RUNNER_<normalized_target>=<spec>`.