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/client/components/ImageUpload.tsx

@@ -1,4 +1,4 @@
-import { useState, useRef } from "react";
+import { useRef, useState } from "react";
 import { apiUpload } from "../lib/api";
 
 interface ImageUploadProps {
@@ -32,10 +32,7 @@ export function ImageUpload({ value, onChange }: ImageUploadProps) {
 
 		setUploading(true);
 		try {
-			const result = await apiUpload<{ filename: string }>(
-				"/api/images",
-				file,
-			);
+			const result = await apiUpload<{ filename: string }>("/api/images", file);
 			onChange(result.filename);
 		} catch {
 			setError("Upload failed. Please try again.");