core: remove @effect/language-service plugin and optimize hot path type performance

- Removed @effect/language-service from both packages/core and packages/opencode tsconfig files and dependencies

- Wrapped mergeDeep calls in config loading and LLM streaming to avoid expensive remeda conditional merge type instantiations in hot paths

- Narrowed Drizzle migrate() overload signature to avoid expensive variance checks during database initialization

These changes reduce TypeScript type-checking overhead and improve startup and runtime performance for config loading, LLM streaming, and database migrations.

packages/opencode/src/storage/db.ts

@@ -48,6 +48,13 @@ type Client = SQLiteBunDatabase
 
 type Journal = { sql: string; timestamp: number; name: string }[]
 
+// Drizzle's migrate overloads trigger expensive variance checks here; narrow to the journal overload we actually use.
+const migrateFromJournal = migrate as unknown as (db: SQLiteBunDatabase, entries: Journal) => void
+
+function applyMigrations(db: SQLiteBunDatabase, entries: Journal) {
+  migrateFromJournal(db, entries)
+}
+
 function time(tag: string) {
   const match = /^(\d{4})(\d{2})(\d{2})(\d{2})(\d{2})(\d{2})/.exec(tag)
   if (!match) return 0
@@ -108,7 +115,7 @@ export const Client = lazy(() => {
         item.sql = "select 1;"
       }
     }
-    migrate(db, entries)
+    applyMigrations(db, entries)
   }
 
   return db