feat: add web UI project registry and onboarding (#427)

Load projects from versioned webui/data/projects.registry.json with profile
mappings, workflow/schema paths, and read-only onboarding checklist UI.
Seeds Gitea-Tools; exposes /projects, /projects/{id}, and /api/projects.

Closes #427

tests/test_webui_skeleton.py

@@ -30,12 +30,17 @@ class TestWebuiSkeleton(unittest.TestCase):
         self.assertIn("Read-only MVP", response.text)
 
     def test_route_stubs_render(self):
-        for path in ("/projects", "/prompts", "/runtime", "/audit"):
+        for path in ("/prompts", "/runtime", "/audit"):
             with self.subTest(path=path):
                 response = self.client.get(path)
                 self.assertEqual(response.status_code, 200)
                 self.assertIn("child issue", response.text.lower())
 
+    def test_projects_is_implemented(self):
+        response = self.client.get("/projects")
+        self.assertEqual(response.status_code, 200)
+        self.assertIn("Gitea-Tools", response.text)
+
     def test_extra_stub_routes(self):
         for path in ("/worktrees", "/leases"):
             with self.subTest(path=path):