refactor: delete server-agent.ts (905 lines)

Remove server recommendation consultation system:
- 30-year expert AI persona
- Session-based information gathering
- Brave Search / Context7 tool integration
- Automatic spec inference

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

migrations/010_add_ddos_sessions.sql

@@ -0,0 +1,19 @@
+-- Migration: Add DDoS Defense Sessions Table
+-- Created: 2026-02-05
+-- Description: Stores DDoS defense consultation sessions
+
+CREATE TABLE IF NOT EXISTS ddos_sessions (
+  user_id TEXT PRIMARY KEY,
+  status TEXT NOT NULL CHECK(status IN ('gathering', 'analyzing', 'recommending', 'completed')),
+  collected_info TEXT, -- JSON: { attack_type?: string, target?: string, symptoms?: string[], traffic_volume?: string }
+  messages TEXT, -- JSON: [{ role: 'user' | 'assistant', content: string }]
+  created_at INTEGER NOT NULL,
+  updated_at INTEGER NOT NULL,
+  expires_at INTEGER NOT NULL
+);
+
+-- Index for cleanup queries (expired sessions)
+CREATE INDEX IF NOT EXISTS idx_ddos_sessions_expires_at ON ddos_sessions(expires_at);
+
+-- Index for status queries (optional, for analytics)
+CREATE INDEX IF NOT EXISTS idx_ddos_sessions_status ON ddos_sessions(status);