Fix note unfiling and relative image paths (#222)

src/lib/utils/paths.ts

@@ -0,0 +1,28 @@
+function pathParts(path: string): string[] {
+	return path.replace(/\\/g, '/').split('/').filter(Boolean);
+}
+
+function pathRoot(path: string): string {
+	const normalized = path.replace(/\\/g, '/');
+	const drive = normalized.match(/^([A-Za-z]:)\//);
+	if (drive) return drive[1].toLowerCase();
+	return normalized.startsWith('/') ? '/' : '';
+}
+
+export function relativePath(fromDirectory: string, targetPath: string): string {
+	const from = pathParts(fromDirectory);
+	const target = pathParts(targetPath);
+	if (pathRoot(fromDirectory) !== pathRoot(targetPath)) return targetPath.replace(/\\/g, '/');
+	const windowsPath = /^[A-Za-z]:[\\/]/.test(fromDirectory) || /^[A-Za-z]:[\\/]/.test(targetPath);
+	const equal = windowsPath
+		? (left: string, right: string) => left.toLowerCase() === right.toLowerCase()
+		: (left: string, right: string) => left === right;
+
+	let common = 0;
+	while (common < from.length && common < target.length && equal(from[common], target[common])) {
+		common++;
+	}
+
+	const result = [...Array(from.length - common).fill('..'), ...target.slice(common)];
+	return result.join('/') || '.';
+}