feat(ui): add maintenance page for task management

* Implement maintenance page with task and log display
* Add backfill and metadata retry functionality
* Integrate grid component for project display in thoughts page
* Update types for maintenance tasks and logs
* Enhance sidebar and shell for new maintenance navigation

migrations/_old/002_create_thoughts.sql

@@ -0,0 +1,19 @@
+create table if not exists thoughts (
+  id         bigserial   primary key,
+  guid       uuid        not null default gen_random_uuid(),
+  content    text        not null,
+  embedding  vector(1536),
+  metadata   jsonb       default '{}'::jsonb,
+  created_at timestamptz default now(),
+  updated_at timestamptz default now(),
+  constraint thoughts_guid_unique unique (guid)
+);
+
+create index if not exists thoughts_embedding_hnsw_idx
+  on thoughts using hnsw (embedding vector_cosine_ops);
+
+create index if not exists thoughts_metadata_gin_idx
+  on thoughts using gin (metadata);
+
+create index if not exists thoughts_created_at_idx
+  on thoughts (created_at desc);