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

app/schemas.py

@@ -126,6 +126,22 @@ class SteeringNoteIn(BaseModel):
         return v.strip() if isinstance(v, str) else v
 
 
+class SteeringNoteUpdate(BaseModel):
+    """``PUT /api/steering/{id}`` body: a new tuning instruction (phase 27).
+
+    Mirrors :class:`SteeringNoteIn` — the note is trimmed *before* the
+    length constraints run, so an empty/whitespace body is a 422 and a
+    full replacement that is ≤2000 chars after the trim still passes.
+    """
+
+    note: str = Field(min_length=1, max_length=2000)
+
+    @field_validator("note", mode="before")
+    @classmethod
+    def _trim_note(cls, v: object) -> object:
+        return v.strip() if isinstance(v, str) else v
+
+
 class SteeringNote(BaseModel):
     """One stored steering note (API shape — ISO-8601 ``created_at``)."""