feat: Automatically detect Reolink NVR channel number (#2259)

- Closes: #2032, #1899 
 -  May or may not help with #2254

- Caution: I do not have an NVR-based Reolink camera to test. If
suddenly Reolink cameras don't work in the card, or in particular if
media doesn't correctly load, this is likely the culprit PR.

src/config/schema/cameras.ts

@@ -250,7 +250,6 @@ export const cameraConfigSchema = z
     reolink: z
       .object({
         url: z.string().optional(),
-        channel: z.number().optional(),
         media_resolution: z
           .enum(['high', 'low'])
           .default(cameraConfigDefault.reolink.media_resolution),