refactor(#182): migrate project-root module to runtime path

sdk/src/query/helpers.ts

@@ -502,9 +502,9 @@ export function planningPaths(projectDir: string, workstream?: string): Planning
 }
 
 // ─── findProjectRoot (multi-repo .planning resolution) ─────────────────────
-// Implementation lives in sdk/src/project-root/index.ts — re-exported here
+// Implementation lives in sdk/src/runtime/project-root.ts — re-exported here
 // so that existing consumers of helpers.ts continue to work unchanged.
-export { findProjectRoot } from '../project-root/index.js';
+export { findProjectRoot } from '../runtime/project-root.js';
 
 // ─── resolvePathUnderProject ───────────────────────────────────────────────
 

sdk/src/runtime/project-root.test.ts

@@ -1,5 +1,5 @@
 /**
- * Pinning tests for sdk/src/project-root/index.ts
+ * Pinning tests for sdk/src/runtime/project-root.ts
  *
  * These tests pin the behaviour of findProjectRoot before the CJS refactor
  * in Cycle 2. They must remain GREEN throughout (never bend the implementation
@@ -14,7 +14,7 @@ import { describe, it, expect, beforeEach, afterEach } from 'vitest';
 import { mkdtemp, rm, writeFile, mkdir } from 'node:fs/promises';
 import { join } from 'node:path';
 import { tmpdir } from 'node:os';
-import { findProjectRoot } from './index.js';
+import { findProjectRoot } from './project-root.js';
 
 describe('findProjectRoot (project-root module)', () => {
   let workspace: string;

sdk/src/runtime/project-root.ts

@@ -10,7 +10,8 @@
  * Bounded by FIND_PROJECT_ROOT_MAX_DEPTH ancestors. Sync I/O.
  *
  * Source of truth for `findProjectRoot` — the CJS artifact at
- * get-shit-done/bin/lib/project-root.generated.cjs is generated from this file.
+ * get-shit-done/bin/lib/project-root.generated.cjs is generated from
+ * sdk/src/runtime/project-root.ts.
  */
 
 import { dirname, resolve, sep, relative, parse as parsePath } from 'node:path';