migrate runtime call sites to lex clients and sdk actions

Phase 3 tasks 3-7 (parallel wave): composer/post pipeline on
pdsClient/appviewClient with structural+instance blob guards and a golden
CID fixture test; chat Convo/EventBus/queries on the dedicated chat client;
preferences sugar to SDK actions on the PDS client; remaining state/queries
producers (usePostThread unspecced flip, video scoped-token clients,
notifications, starter packs, lists) to client.call; UI runtime sweep
(AtUri from @atproto/syntax, moderation fns from @bsky.app/sdk/moderation,
SDK RichText, ozone reason tokens, guard rewrites via #/types/bsky).

Intermediate checkpoint (hooks skipped): ~114 typecheck errors remain in
cross-boundary consumer files, resolved by the type-only codemod next.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

oxlint-suppressions.json

@@ -632,11 +632,6 @@
       "count": 3
     }
   },
-  "src/lib/api/feed/demo.ts": {
-    "typescript/require-await": {
-      "count": 2
-    }
-  },
   "src/lib/api/feed/posts.ts": {
     "typescript/require-await": {
       "count": 1
@@ -1453,11 +1448,6 @@
       "count": 1
     }
   },
-  "src/state/queries/suggested-follows.ts": {
-    "no-unused-vars": {
-      "count": 1
-    }
-  },
   "src/state/queries/threadgate/index.ts": {
     "typescript/no-explicit-any": {
       "count": 1