fix(pds): 413 body shape + register app.bsky.feed.like/repost

Three fixes for the integration test plan:

1. Layer order in tauri.conf.json: `body_limit_fallback` must
   wrap `upload_blob_body_limit` so the JSON override is in
   effect when the 413 fires. Swapped.

2. Type annotation on the `from_fn` middleware:
   `.layer::<_, std::convert::Infallible>(...)`. The function
   never errors, so the second type param is Infallible.

3. Register the standard `app.bsky.feed.like` and
   `app.bsky.feed.repost` lexicons so the like/repost
   endpoints (which create records of those collections) pass
   the lex validator. We only ship what the PDS actually lets
   users create server-side; anything else passes `validate: false`.

The 'unprocessable entity' style message and 'unknown lexicon'
errors that came up during manual testing are now gone.

Also dropped the stuck migration-2 row from `_sqlx_migrations`
on the dev DB so the new lex schemas apply.

lexicons/app/bsky/feed/like.json

@@ -0,0 +1,18 @@
+{
+  "lexicon": 1,
+  "id": "app.bsky.feed.like",
+  "defs": {
+    "main": {
+      "type": "record",
+      "key": "tid",
+      "record": {
+        "type": "object",
+        "required": ["subject", "createdAt"],
+        "properties": {
+          "subject": { "type": "ref", "ref": "com.atproto.repo.strongRef" },
+          "createdAt": { "type": "datetime" }
+        }
+      }
+    }
+  }
+}

lexicons/app/bsky/feed/repost.json

@@ -0,0 +1,18 @@
+{
+  "lexicon": 1,
+  "id": "app.bsky.feed.repost",
+  "defs": {
+    "main": {
+      "type": "record",
+      "key": "tid",
+      "record": {
+        "type": "object",
+        "required": ["subject", "createdAt"],
+        "properties": {
+          "subject": { "type": "ref", "ref": "com.atproto.repo.strongRef" },
+          "createdAt": { "type": "datetime" }
+        }
+      }
+    }
+  }
+}