Initial import: the house-style lint rules as a crafter-build module

Moved out of Crafter.Build's lint-rules.h so a project.cpp pulls them in
with `#pragma crafter dependency` + `import Crafter.LintRules;` instead of
copying a header. The rule bodies are unchanged; format-concat now sits
with the other transforms (it rewrites, it was registered as a report),
and the helpers are module-internal. tests/HouseRules moved along with
the rules and links crafter-build from git, or the sibling checkout with
--local.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

project.cpp

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: LGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
+
+import std;
+import Crafter.Build;
+namespace fs = std::filesystem;
+using namespace Crafter;
+
+extern "C" Configuration CrafterBuildProject(std::span<const std::string_view> args) {
+    std::vector<std::string> depArgs(args.begin(), args.end());
+    const bool useLocal = std::erase(depArgs, "--local") > 0;
+
+    Configuration cfg;
+    cfg.path = "./";
+    cfg.name = "Crafter.LintRules";
+    cfg.outputName = "Crafter.LintRules";
+    cfg.type = ConfigurationType::LibraryStatic;
+    ApplyStandardArgs(cfg, args);
+    // No dependency on Crafter.Build, on purpose. The rules only ever run
+    // inside a crafter-build process, which provides the symbols, and a host
+    // build already sees the Crafter.Build modules through the PCM cache
+    // crafter-build keeps for its own project files — declaring the library
+    // here would make every consumer clone and build all of crafter-build
+    // just to lint.
+    std::array<fs::path, 1> ifaces = { "interfaces/Crafter.LintRules" };
+    std::array<fs::path, 0> impls = {};
+    cfg.GetInterfacesAndImplementations(ifaces, impls);
+
+    // The rule test compiles the module as its own interface and links
+    // crafter-build to run the linter in-process: from git by default, or
+    // the sibling checkout with `crafter-build test --local`. Host only,
+    // like the rules themselves.
+    if (cfg.target == "x86_64-pc-linux-gnu") {
+        Configuration* build = useLocal
+            ? LocalProject({ .projectFile = "../Crafter.Build/project.cpp", .args = depArgs })
+            : GitProject({ .source = { .url = "https://forgejo.catcrafts.net/Catcrafts/Crafter.Build.git" }, .args = depArgs });
+        cfg.AddTest("HouseRules", ifaces).Dependencies({ build });
+    }
+    return cfg;
+}