feat: migrate schema to DATE type, add test infrastructure

- Migrate due_date/next_occurrence columns from TIMESTAMPTZ to DATE
- Update serializeRow() to distinguish DATE vs TIMESTAMPTZ serialization
- Simplify frontend date parsing (no more timezone workarounds)
- Add Vitest + Testing Library test infrastructure
- Add initial date parsing/formatting unit tests
- Update package.json with dev dependencies (vitest, testing-library, jsdom)

src/app/api/projects/[id]/route.ts

@@ -0,0 +1,95 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { Pool } from 'pg';
+
+const pool = new Pool({
+  connectionString: process.env.DATABASE_URL || 'postgresql://vixtix:vixtix_secret@localhost:5433/vixtix',
+});
+
+function serializeRow(row: Record<string, any>): Record<string, any> {
+  const toCamel = (str: string) => str.replace(/_([a-z])/g, (_, c) => c.toUpperCase());
+  const result: Record<string, any> = {};
+  for (const [key, value] of Object.entries(row)) {
+    const camelKey = toCamel(key);
+    if (value instanceof Date) {
+      result[camelKey] = value.toISOString();
+    } else {
+      result[camelKey] = value;
+    }
+  }
+  return result;
+}
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const { id } = await params;
+
+  try {
+    const result = await pool.query('SELECT * FROM projects WHERE id = $1', [id]);
+
+    if (result.rows.length === 0) {
+      return NextResponse.json({ error: 'Project not found' }, { status: 404 });
+    }
+
+    return NextResponse.json(serializeRow(result.rows[0]));
+  } catch (error) {
+    console.error('Error fetching project:', error);
+    return NextResponse.json({ error: 'Failed to fetch project' }, { status: 500 });
+  }
+}
+
+export async function PUT(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const { id } = await params;
+  let body;
+
+  try {
+    body = await request.json();
+  } catch {
+    return NextResponse.json({ error: 'Invalid JSON' }, { status: 400 });
+  }
+
+  const { name, description, color, sortOrder } = body;
+
+  if (!name?.trim()) {
+    return NextResponse.json({ error: 'Name is required' }, { status: 400 });
+  }
+
+  try {
+    const result = await pool.query(
+      `UPDATE projects SET name = $1, description = $2, color = $3, sort_order = $4 WHERE id = $5 RETURNING *`,
+      [name.trim(), description?.trim() || '', color, sortOrder, id]
+    );
+
+    if (result.rows.length === 0) {
+      return NextResponse.json({ error: 'Project not found' }, { status: 404 });
+    }
+
+    return NextResponse.json(serializeRow(result.rows[0]));
+  } catch (error) {
+    console.error('Error updating project:', error);
+    return NextResponse.json({ error: 'Failed to update project' }, { status: 500 });
+  }
+}
+
+export async function DELETE(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> }
+) {
+  const { id } = await params;
+
+  try {
+    // Delete all tasks in the project first
+    await pool.query('DELETE FROM tasks WHERE project_id = $1', [id]);
+    // Then delete the project
+    await pool.query('DELETE FROM projects WHERE id = $1', [id]);
+
+    return NextResponse.json({ success: true });
+  } catch (error) {
+    console.error('Error deleting project:', error);
+    return NextResponse.json({ error: 'Failed to delete project' }, { status: 500 });
+  }
+}