Move compression thresholds to a feature-local constants file

Per Frontend Spec (A2.4 pre-merge note): MAX_UPLOAD_SIZE was hardcoded to
100 MB and would force-compress 100-300 MB files that should skip. Reads
from VIDEO_MAX_SIZE now. Pulled the target/passthrough bitrate and max
dimension out of compress.ts into src/lib/media/video/constants.ts so the
compression contract lives in one place without bloating the global
constants file.

src/lib/media/video/compress.ts

@@ -1,14 +1,19 @@
 import {type ImagePickerAsset} from 'expo-image-picker'
 
-import {SUPPORTED_MIME_TYPES, type SupportedMimeTypes} from '#/lib/constants'
+import {
+  SUPPORTED_MIME_TYPES,
+  type SupportedMimeTypes,
+  VIDEO_MAX_SIZE,
+} from '#/lib/constants'
 import {logger} from '#/logger'
 import {compress, probe} from '../../../../modules/expo-bluesky-video-compress'
+import {
+  COMPRESSION_MAX_DIMENSION,
+  COMPRESSION_PASSTHROUGH_BITRATE,
+  COMPRESSION_TARGET_BITRATE,
+} from './constants'
 import {type CompressedVideo} from './types'
 
-const PASSTHROUGH_BITRATE = 5_000_000
-const PASSTHROUGH_MAX_DIMENSION = 1920
-const MAX_UPLOAD_SIZE = 100 * 1000 * 1000
-
 export async function compressVideo(
   file: ImagePickerAsset,
   opts?: {
@@ -49,8 +54,8 @@ export async function compressVideo(
   const result = await compress(
     file.uri,
     {
-      targetBitrate: 3_000_000,
-      maxSize: PASSTHROUGH_MAX_DIMENSION,
+      targetBitrate: COMPRESSION_TARGET_BITRATE,
+      maxSize: COMPRESSION_MAX_DIMENSION,
       codec: 'h264',
     },
     {
@@ -92,14 +97,14 @@ function shouldCompress(
     return true
   }
 
-  if (metadata.fileSize > MAX_UPLOAD_SIZE) {
+  if (metadata.fileSize > VIDEO_MAX_SIZE) {
     logger.debug(`shouldCompress: yes (file too large: ${sizeMB}MB)`)
     return true
   }
 
   if (
-    metadata.bitrate <= PASSTHROUGH_BITRATE &&
-    maxDimension <= PASSTHROUGH_MAX_DIMENSION
+    metadata.bitrate <= COMPRESSION_PASSTHROUGH_BITRATE &&
+    maxDimension <= COMPRESSION_MAX_DIMENSION
   ) {
     logger.debug(
       `shouldCompress: no (${bitrateKbps}kbps, ${maxDimension}px, ${sizeMB}MB)`,
@@ -107,7 +112,7 @@ function shouldCompress(
     return false
   }
 
-  if (metadata.bitrate > PASSTHROUGH_BITRATE) {
+  if (metadata.bitrate > COMPRESSION_PASSTHROUGH_BITRATE) {
     logger.debug(`shouldCompress: yes (bitrate ${bitrateKbps}kbps)`)
   } else {
     logger.debug(`shouldCompress: yes (dimension ${maxDimension}px)`)

src/lib/media/video/constants.ts

@@ -0,0 +1,8 @@
+// Target encode bitrate when we do compress. Matches the web path.
+export const COMPRESSION_TARGET_BITRATE = 3_000_000 // 3mbps
+// Source files at or under this bitrate skip compression (paired with
+// COMPRESSION_MAX_DIMENSION). Slightly above the encode target so we
+// don't re-encode files that are already close to what we'd produce.
+export const COMPRESSION_PASSTHROUGH_BITRATE = 5_000_000 // 5mbps
+// Output dimension cap when compressing, and skip threshold for source files.
+export const COMPRESSION_MAX_DIMENSION = 1920