resolve hwaccel per camera and clarify recording retention

The hwaccel step listed every preset Frigate ships, so an Intel box was offered Raspberry Pi and Rockchip decoding, and the codec specific presets (`preset-intel-qsv-h264` vs `-h265`) were offered as global values that break as soon as two cameras use different codecs. `/hardware/hwaccel` now returns the decoding families the probed hardware can actually use, each carrying a preset per codec, and the wizard resolves the family against the detect stream codec the camera wizard already probed: one global `ffmpeg.hwaccel_args` when every camera agrees, per-camera `cameras.<name>.ffmpeg.hwaccel_args` when they don't. The global stays on `auto` in that case so cameras added later still resolve at startup. A gen13+ Intel machine keeps its QuickSync recommendation with mixed h264 and h265 cameras instead of dropping to vaapi.

The recording step's "Days to retain recordings" only wrote alert and detection retention, and the storage estimate under it assumed continuous recording. It now asks what to record in plain language, writes `record.continuous.days` to match, shows the estimate only for continuous, and drops the spinner arrows on the number input.

docs/static/frigate-api.yaml

@@ -4053,6 +4053,58 @@ paths:
       security:
         - frigateAdminAuth: []
       x-required-role: admin
+  /hardware/hwaccel:
+    get:
+      tags:
+        - Hardware
+      summary: Hwaccel Recommendation
+      description: |-
+        **Access:** Admin role required.
+
+        Get the hardware decoding this system can do.
+
+        Args:
+            detector: Hardware key of the detection hardware in use, which biases
+                the recommendation toward that hardware's GPU
+            codecs: Comma separated codecs of the streams that will be decoded,
+                used to drop families that cannot decode one of them
+
+        Returns:
+            The recommended family (empty when none fits) and every usable family
+      operationId: hwaccel_recommendation_hardware_hwaccel_get
+      parameters:
+        - name: detector
+          in: query
+          required: false
+          schema:
+            anyOf:
+              - type: string
+              - type: 'null'
+            title: Detector
+        - name: codecs
+          in: query
+          required: false
+          schema:
+            anyOf:
+              - type: string
+              - type: 'null'
+            title: Codecs
+      responses:
+        '200':
+          description: Successful Response
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/HwaccelRecommendation'
+        '422':
+          description: Validation Error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/HTTPValidationError'
+      security:
+        - frigateAdminAuth: []
+      x-required-role: admin
   /events:
     get:
       tags:
@@ -8670,6 +8722,43 @@ components:
         - label
       title: HardwareUnit
       description: One physical piece of hardware.
+    HwaccelFamily:
+      properties:
+        key:
+          type: string
+          title: Family key
+          description: Stable identifier for this kind of hardware decoding.
+        presets:
+          additionalProperties:
+            type: string
+          type: object
+          title: Presets
+          description: The ffmpeg preset for each codec this family decodes, or 
+            a single 'any' preset when it decodes every codec.
+      type: object
+      required:
+        - key
+        - presets
+      title: HwaccelFamily
+      description: A kind of hardware decoding, and the presets that drive it.
+    HwaccelRecommendation:
+      properties:
+        recommended:
+          type: string
+          title: Recommended family
+          description: Key of the family that fits this system best, or an empty
+            string when none does.
+        available:
+          items:
+            $ref: '#/components/schemas/HwaccelFamily'
+          type: array
+          title: Available families
+          description: Every family this system's hardware can use, best first.
+      type: object
+      required:
+        - recommended
+      title: HwaccelRecommendation
+      description: The hardware decoding this system can do.
     Last24HoursReview:
       properties:
         reviewed_alert: