feat(rag): global tuning manager — /tuning.html + PUT /api/steering/{id}: create, edit, list, delete steering notes without a chat

tests/integration/test_api.py

@@ -57,6 +57,7 @@ def test_suggestions_honors_bor_suggestions_env_override(monkeypatch) -> None:
         ("/sources.html", "Knowledge base"),
         ("/document.html", "Brain of Reese"),  # phase 10: viewer page
         ("/login.html", "Sign in"),  # phase 16: admin sign-in page
+        ("/tuning.html", "Global Tuning"),  # phase 27: global tuning page
     ],
 )
 def test_html_pages_served_locally_no_cdn(client, path: str, marker: str) -> None:
@@ -78,6 +79,7 @@ def test_styles_and_js_served(client) -> None:
     assert client.get("/assets/document.js").status_code == 200  # phase 10: viewer page
     assert client.get("/assets/login.js").status_code == 200  # phase 16: login page
     assert client.get("/assets/document-modal.js").status_code == 200  # phase 26: modal module
+    assert client.get("/assets/tuning.js").status_code == 200  # phase 27: tuning page
 
 
 # Emoji code points banned from UI chrome (phase 08): the pictograph
@@ -108,6 +110,7 @@ def _find_emoji(text: str) -> list[str]:
         "/sources.html",
         "/document.html",
         "/login.html",  # phase 16
+        "/tuning.html",  # phase 27
         "/assets/app.js",
         "/assets/sources.js",
         "/assets/markdown.js",