chore: auto-fix Biome formatting and configure lint rules

Run biome check --write --unsafe to fix tabs, import ordering, and
non-null assertions across entire codebase. Disable a11y rules not
applicable to this single-user app. Exclude auto-generated routeTree.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/db/seed.ts

@@ -2,13 +2,13 @@ import { db } from "./index.ts";
 import { categories } from "./schema.ts";
 
 export function seedDefaults() {
-  const existing = db.select().from(categories).all();
-  if (existing.length === 0) {
-    db.insert(categories)
-      .values({
-        name: "Uncategorized",
-        icon: "package",
-      })
-      .run();
-  }
+	const existing = db.select().from(categories).all();
+	if (existing.length === 0) {
+		db.insert(categories)
+			.values({
+				name: "Uncategorized",
+				icon: "package",
+			})
+			.run();
+	}
 }