feat: Add task-mcp server for task management via MCP

Implements 10 MCP tools for task management:
- CRUD: task_add, task_list, task_show, task_close, task_update
- Search: task_similar (pgvector), task_context
- Relations: task_link, task_checklist_add, task_checklist_toggle

Uses PostgreSQL with pgvector for semantic search via LiteLLM embeddings.
Connects via SSH tunnel to docker-host:5435.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/db.ts

@@ -0,0 +1,120 @@
+import pg from 'pg';
+const { Pool } = pg;
+
+// Configuration from environment variables
+const config = {
+  host: process.env.DB_HOST || 'localhost',
+  port: parseInt(process.env.DB_PORT || '5432'),
+  database: process.env.DB_NAME || 'litellm',
+  user: process.env.DB_USER || 'litellm',
+  password: process.env.DB_PASSWORD || 'litellm',
+  max: 5,
+  idleTimeoutMillis: 30000,
+  connectionTimeoutMillis: 5000,
+};
+
+// Create connection pool
+const pool = new Pool(config);
+
+// Log connection errors
+pool.on('error', (err) => {
+  console.error('Unexpected database error:', err);
+});
+
+/**
+ * Execute a query and return all rows
+ */
+export async function query<T = Record<string, unknown>>(
+  text: string,
+  params?: unknown[]
+): Promise<T[]> {
+  const result = await pool.query(text, params);
+  return result.rows as T[];
+}
+
+/**
+ * Execute a query and return the first row
+ */
+export async function queryOne<T = Record<string, unknown>>(
+  text: string,
+  params?: unknown[]
+): Promise<T | null> {
+  const result = await pool.query(text, params);
+  return (result.rows[0] as T) || null;
+}
+
+/**
+ * Execute a query without returning results (INSERT, UPDATE, DELETE)
+ */
+export async function execute(
+  text: string,
+  params?: unknown[]
+): Promise<number> {
+  const result = await pool.query(text, params);
+  return result.rowCount || 0;
+}
+
+/**
+ * Get the next task ID for a project
+ */
+export async function getNextTaskId(projectKey: string): Promise<string> {
+  const result = await queryOne<{ next_id: number }>(
+    `INSERT INTO task_sequences (project, next_id) VALUES ($1, 1)
+     ON CONFLICT (project) DO UPDATE SET next_id = task_sequences.next_id + 1
+     RETURNING next_id`,
+    [projectKey]
+  );
+  return `${projectKey}-${result?.next_id || 1}`;
+}
+
+/**
+ * Get project key from name, or generate one
+ */
+export async function getProjectKey(projectName: string): Promise<string> {
+  // First check if already registered
+  const existing = await queryOne<{ key: string }>(
+    `SELECT key FROM projects WHERE name = $1 LIMIT 1`,
+    [projectName]
+  );
+
+  if (existing) {
+    return existing.key;
+  }
+
+  // Generate a key from the name (uppercase first letters)
+  let generated = projectName.replace(/[a-z]/g, '').slice(0, 4);
+  if (!generated) {
+    generated = projectName.slice(0, 3).toUpperCase();
+  }
+
+  // Register the new project
+  await execute(
+    `INSERT INTO projects (key, name) VALUES ($1, $2)
+     ON CONFLICT (key) DO NOTHING`,
+    [generated, projectName]
+  );
+
+  return generated;
+}
+
+/**
+ * Test database connection
+ */
+export async function testConnection(): Promise<boolean> {
+  try {
+    await query('SELECT 1');
+    return true;
+  } catch (error) {
+    console.error('Database connection failed:', error);
+    return false;
+  }
+}
+
+/**
+ * Close the connection pool
+ */
+export async function close(): Promise<void> {
+  await pool.end();
+}
+
+export default pool;