feat(install-targets): add claude-project (per-project Claude Code) adapter

Completes the install-target matrix for Claude Code. Until now, ECC's
Claude support was home-scope only (~/.claude/) via the `claude` target.
This adds a project-scope counterpart (./.claude/) via a new
`claude-project` target so teams can install ECC per-repo without
contaminating ~/.claude/ — matching the existing project-scope adapters
for Cursor, Antigravity, Gemini, CodeBuddy, Joycode, and Zed.

Symmetric with `claude`:
- Same namespace under rules/ecc and skills/ecc
- Same docs/<locale> handling for --locale
- Same hooks placeholder substitution for hooks.json
- Reuses claude-home's destination-mapping logic 1:1

Use cases:
- Monorepos with multiple Flow-managed projects
- Teams that want ECC scoped per-project without touching ~/.claude/
- Per-project skill/rule isolation when global install isn't desirable

No breaking change: existing --target claude continues to route to
claude-home (user-scope) unchanged. New target is opt-in.

Tests
-----
- 4 new tests in tests/lib/install-targets.test.js
  (root resolution, lookup-by-id, plan parity with claude, foreign-path filtering)
- All install-target regression guards (schema enum / SUPPORTED_INSTALL_TARGETS)
  still pass
- End-to-end smoke: `--target claude-project --profile minimal --dry-run`
  emits 359 ops with destinations rooted at <projectRoot>/.claude/ (parity
  with --target claude which emits 359 ops rooted at ~/.claude/)

scripts/lib/install-targets/claude-project.js

@@ -0,0 +1,91 @@
+const path = require('path');
+
+const {
+  createInstallTargetAdapter,
+  createRemappedOperation,
+  isForeignPlatformPath,
+  normalizeRelativePath,
+} = require('./helpers');
+
+const CLAUDE_ECC_NAMESPACE = 'ecc';
+
+function getClaudeManagedDestinationPath(adapter, sourceRelativePath, input) {
+  const normalizedSourcePath = normalizeRelativePath(sourceRelativePath);
+  const targetRoot = adapter.resolveRoot(input);
+
+  if (normalizedSourcePath === 'rules') {
+    return path.join(targetRoot, 'rules', CLAUDE_ECC_NAMESPACE);
+  }
+
+  if (normalizedSourcePath.startsWith('rules/')) {
+    return path.join(
+      targetRoot,
+      'rules',
+      CLAUDE_ECC_NAMESPACE,
+      normalizedSourcePath.slice('rules/'.length)
+    );
+  }
+
+  if (normalizedSourcePath === 'skills') {
+    return path.join(targetRoot, 'skills', CLAUDE_ECC_NAMESPACE);
+  }
+
+  if (normalizedSourcePath.startsWith('skills/')) {
+    return path.join(
+      targetRoot,
+      'skills',
+      CLAUDE_ECC_NAMESPACE,
+      normalizedSourcePath.slice('skills/'.length)
+    );
+  }
+
+  if (normalizedSourcePath === 'docs' || normalizedSourcePath.startsWith('docs/')) {
+    return path.join(targetRoot, normalizedSourcePath);
+  }
+
+  return null;
+}
+
+module.exports = createInstallTargetAdapter({
+  id: 'claude-project',
+  target: 'claude-project',
+  kind: 'project',
+  rootSegments: ['.claude'],
+  installStatePathSegments: ['ecc', 'install-state.json'],
+  nativeRootRelativePath: '.claude-plugin',
+  planOperations(input, adapter) {
+    const modules = Array.isArray(input.modules)
+      ? input.modules
+      : (input.module ? [input.module] : []);
+    const planningInput = {
+      repoRoot: input.repoRoot,
+      projectRoot: input.projectRoot,
+      homeDir: input.homeDir,
+    };
+
+    return modules.flatMap(module => {
+      const paths = Array.isArray(module.paths) ? module.paths : [];
+      return paths
+        .filter(p => !isForeignPlatformPath(p, 'claude'))
+        .map(sourceRelativePath => {
+          const managedDestinationPath = getClaudeManagedDestinationPath(
+            adapter,
+            sourceRelativePath,
+            planningInput
+          );
+
+          if (managedDestinationPath) {
+            return createRemappedOperation(
+              adapter,
+              module.id,
+              sourceRelativePath,
+              managedDestinationPath,
+              { strategy: 'preserve-relative-path' }
+            );
+          }
+
+          return adapter.createScaffoldOperation(module.id, sourceRelativePath, planningInput);
+        });
+    });
+  },
+});

scripts/lib/install-targets/registry.js

@@ -1,5 +1,6 @@
 const antigravityProject = require('./antigravity-project');
 const claudeHome = require('./claude-home');
+const claudeProject = require('./claude-project');
 const codebuddyProject = require('./codebuddy-project');
 const codexHome = require('./codex-home');
 const cursorProject = require('./cursor-project');
@@ -11,6 +12,7 @@ const zedProject = require('./zed-project');
 
 const ADAPTERS = Object.freeze([
   claudeHome,
+  claudeProject,
   cursorProject,
   antigravityProject,
   codexHome,