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.
