Add recording keyframe analysis to camera probe dialog (#23453)

* backend: endpoint and util funcs

* tests

* frontend and i18n

* update openapi spec

* add tip to docs

docs/docs/troubleshooting/recordings.md

@@ -121,6 +121,12 @@ If segments are only ~1 second instead of ~10 seconds, the camera is sending cor
 - **Changing codec, bitrate, or resolution mid-stream** — Any encoding changes during an active stream can cause unpredictable segment splitting.
 - **Camera firmware bugs** — Check for firmware updates from your camera manufacturer.
 
+:::tip
+
+You don't have to run `ffprobe` by hand to catch this. Open a camera's **Camera Probe Info** dialog (the info icon on the System → Metrics → Cameras page) and check the **Keyframe analysis** section. It probes the record stream and flags sparse or variable keyframes, which is what smart/"+" codecs (H.264+/H.265+) and long keyframe intervals produce.
+
+:::
+
 ### Step 4: Check for a stuck detector
 
 If the detect stream is not processing frames, segments will accumulate. Common causes:

docs/static/frigate-api.yaml

@@ -400,6 +400,35 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/HTTPValidationError"
+  /keyframe_analysis:
+    get:
+      tags:
+        - Camera
+      summary: Keyframe Analysis
+      description: >-
+        Probe a camera's record stream and classify its keyframe spacing.
+        Detects smart/+ codecs and long/variable GOPs that degrade recording.
+      operationId: keyframe_analysis_keyframe_analysis_get
+      parameters:
+        - name: camera
+          in: query
+          required: false
+          schema:
+            type: string
+            default: ""
+            title: Camera
+      responses:
+        "200":
+          description: Successful Response
+          content:
+            application/json:
+              schema: {}
+        "422":
+          description: Validation Error
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/HTTPValidationError"
   /ffprobe/snapshot:
     get:
       tags: