fix(find-browse): resolve source-checkout layout <git-root>/browse/dist/browse[.exe]

windows-setup-e2e.yml runs `bun browse/src/find-browse.ts` against a
freshly-built repo where binaries land at browse/dist/browse.exe (no
.claude/skills/gstack/ install layout). The previous markers chain
only matched .codex/.agents/.claude prefixed paths, so find-browse
exited "not found" even when the binary was present.

Adds a source-checkout fallback after the marker scan: if no
installed layout resolves but <git-root>/browse/dist/browse[.exe]
exists, return that. Three real callers hit this path:
- gstack repo dev workflow before `./setup` runs
- windows-setup-e2e.yml CI (the breakage that surfaced this)
- make-pdf consumers running from a sibling source checkout

Smoke-verified: a fresh git repo with browse/dist/browse on disk now
resolves through the source-checkout branch (was returning null
before this commit).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

browse/src/find-browse.ts

@@ -65,6 +65,16 @@ export function locateBinary(): string | null {
       const found = findExecutable(local);
       if (found) return found;
     }
+
+    // Source-checkout fallback (no installed skill layout — the binary
+    // lives directly at <repo>/browse/dist/browse[.exe]). Hit by:
+    // - gstack repo dev workflow before `./setup` runs
+    // - the windows-setup-e2e.yml CI workflow which builds binaries
+    //   in place but never installs them under a marker dir
+    // - make-pdf consumers running from a sibling source checkout
+    const sourceCheckout = join(root, 'browse', 'dist', 'browse');
+    const sourceFound = findExecutable(sourceCheckout);
+    if (sourceFound) return sourceFound;
   }
 
   // Global fallback

browse/test/find-browse.test.ts

@@ -47,4 +47,15 @@ describe('locateBinary', () => {
     expect(typeof locateBinary).toBe('function');
     expect(locateBinary.length).toBe(0);
   });
+
+  test('source-checkout fallback resolves <git-root>/browse/dist/browse[.exe]', () => {
+    // The windows-setup-e2e.yml workflow builds binaries directly under
+    // browse/dist/ (no .claude/skills/gstack/ install layout). find-browse
+    // must resolve those — otherwise every fresh build that hasn't run
+    // ./setup yet looks broken. Static pin so a future refactor that
+    // drops the source-checkout branch trips this test.
+    const src = require('fs').readFileSync(require('path').join(__dirname, '../src/find-browse.ts'), 'utf-8');
+    expect(src).toContain('Source-checkout fallback');
+    expect(src).toContain("join(root, 'browse', 'dist', 'browse')");
+  });
 });