feat(appview): profile cache + Jetstream indexing + denormalised counts

Adds the AppView-side half of the profile feature so non-local-PDS
authors also get their profile metadata indexed (the Jetstream
identity event stream only carries the handle, not display name /
bio / avatar). The PDS-push path was already wired by the previous
commit; this lands the Jetstream path.

Migration 0005:

* `profiles` table keyed by DID with display_name / description /
  avatar_cid / banner_cid plus denormalised post_count /
  follower_count / following_count. Backfilled from the posts
  table on apply.
* `posts.avatar_cid` column — populated from the profiles cache
  at `upsert_post` time so the PostCard can render an avatar
  inline without a per-row PDS round trip.

Migration 0007 (clean-up): the original 0005 also created a
`LOWER(handle)` index that no query uses; this drops it
idempotently so dev DBs that already applied 0005 converge.

Indexer (`crates/appview/src/indexer.rs`):

* New `app.bsky.actor.profile` arm in `apply_commit` calls
  `upsert_profile` on create, DELETEs the row on delete. Handle
  is looked up from `posts` (the Jetstream commit envelope
  doesn't carry it).
* `upsert_post` signature is now `&mut PostRow` so it can fill
  `row.avatar_cid` from the profiles cache; the ON CONFLICT
  clause uses `COALESCE(EXCLUDED, posts)` so re-indexing doesn't
  overwrite an already-known avatar.
* `upsert_profile` writes display_name / description /
  avatar_cid / banner_cid + the denormalised counts.
* `blob_link_of` helper accepts both `{ $type, ref.$link }`
  and legacy flat `{ $link }` blob-ref shapes.

Ingest (`crates/appview/src/ingest.rs`):

* `app.bsky.actor.profile` create/delete arms in the PDS-push
  path. The handle-fallback previously did `SELECT handle FROM
  users WHERE did = $1` — but the AppView has no `users` table
  (it's PDS-owned state). Replaced with a simple use-what-the-PDS-
  sent approach; the handle_sync worker fills the column later.

Routes (`crates/appview/src/routes.rs`):

* `resolve_profile` reads the denormalised profile fields from
  the cache. When no profile row exists the `post_count` fallback
  uses a live `SELECT COUNT(*)` instead of `posts.len()`, so
  prolific authors without a profile row report the real count
  rather than the 50-post slice cap.

Tests (DB-gated, run when DATABASE_URL_APPVIEW is set):

* `blob_link_of_modern_shape` / `_legacy_flat_link` /
  `_missing_field`.
* `upsert_profile_round_trip` — insert + replace semantics.
* `apply_commit_indexes_profile_create` — end-to-end Jetstream
  arm + delete.

crates/appview/src/ingest.rs

@@ -128,7 +128,7 @@ async fn apply(
                 .clone()
                 .unwrap_or_else(|| serde_json::json!({"text": "", "createdAt": chrono::Utc::now().to_rfc3339()}));
             let cid = req.cid.clone().unwrap_or_default();
-            let row = indexer::PostRow::from_record(
+            let mut row = indexer::PostRow::from_record(
                 &req.did,
                 &req.rkey,
                 &req.collection,
@@ -136,7 +136,7 @@ async fn apply(
                 &record,
                 req.handle.as_deref(),
             );
-            indexer::upsert_post(&state.db, &row).await.map_err(db_err)?;
+            indexer::upsert_post(&state.db, &mut row).await.map_err(db_err)?;
             Ok(true)
         }
         ("app.twi.post", "delete") | ("app.bsky.feed.post", "delete") => {
@@ -219,6 +219,39 @@ async fn apply(
                 .map_err(db_err)?;
             Ok(true)
         }
+        ("app.bsky.actor.profile", "create") if req.rkey == "self" => {
+            // Profile record push from the PDS — populate the
+            // `profiles` cache so the ProfileView-Page and PostCard
+            // avatar get the new display name / bio / avatar / banner
+            // without waiting for the next handle-sync pass.
+            let record = match &req.record {
+                Some(r) if !r.is_null() => r.clone(),
+                _ => return Ok(false),
+            };
+            // Use the handle the PDS provided when present. We
+            // deliberately do NOT fall back to a DB lookup here:
+            // the AppView has no `users` table — the PDS owns that
+            // state. If the PDS omits the handle, we write an empty
+            // string and the `handle_sync` worker (or a subsequent
+            // Jetstream `identity` event) will fill it in.
+            let handle = req
+                .handle
+                .clone()
+                .filter(|h| !h.is_empty())
+                .unwrap_or_default();
+            indexer::upsert_profile(&state.db, &req.did, &handle, &record)
+                .await
+                .map_err(db_err)?;
+            Ok(true)
+        }
+        ("app.bsky.actor.profile", "delete") if req.rkey == "self" => {
+            sqlx::query("DELETE FROM profiles WHERE did = $1")
+                .bind(&req.did)
+                .execute(&state.db)
+                .await
+                .map_err(db_err)?;
+            Ok(true)
+        }
         (coll, action) => {
             // Unrecognised collection/action — return ok=false so the PDS
             // doesn't retry. Future collections should be added above.