Merge main into gallery-embed, migrate off local shim

Bumps @atproto/api to 0.20.9, which ships the generated
`AppBskyEmbedGallery` namespace and `DraftPost.embedGallery`. Swaps every
`#/lib/api/gallery-embed-shim` import to `@atproto/api`, deletes the
shim, drops the local `DraftPostWithGallery` widen-types, and adds the
narrowing calls (`isViewImage`, `isDraftEmbedImage`) the real lexicon
unions require.

The merge also auto-resolves an inline image-restore block in
`drafts/state/api.ts` against main's typing tweak — main switched to
`satisfies ComposerImage` and `NonNullable<typeof img>`, which here move
into the existing `restoreDraftImages` helper that's now shared by both
the images and gallery restore paths.

pnpm-lock.yaml

@@ -242,8 +242,8 @@ importers:
   .:
     dependencies:
       '@atproto/api':
-        specifier: 0.20.8
-        version: 0.20.8
+        specifier: 0.20.9
+        version: 0.20.9
       '@atproto/syntax':
         specifier: 0.6.1
         version: 0.6.1
@@ -877,8 +877,8 @@ packages:
       graphql:
         optional: true
 
-  '@atproto/api@0.20.8':
-    resolution: {integrity: sha512-rTkA6kOmA2axSrg6VgpdXpsCFWpofnHBOn6pKg69Ju5MpIHqk4haQMgjBcVh1G3kUxzwgSAr7SYrPS3dFe5Etg==}
+  '@atproto/api@0.20.9':
+    resolution: {integrity: sha512-Yuw7Ewn+yMJZ8GskbuvI3lKPW65rsXic1xjFA2Dpq6H8WjVYs6xNZ31bkwtTYDDwjKIZcJmAVbAVgdfjo4T9iw==}
     engines: {node: '>=22'}
 
   '@atproto/common-web@0.5.0':
@@ -9493,7 +9493,7 @@ snapshots:
 
   '@0no-co/graphql.web@1.2.0': {}
 
-  '@atproto/api@0.20.8':
+  '@atproto/api@0.20.9':
     dependencies:
       '@atproto/common-web': 0.5.0
       '@atproto/lexicon': 0.7.1