Add PostgreSQL database persistence

- Add connect_machines, connect_sessions, connect_session_events, connect_support_codes tables
- Implement db module with connection pooling (sqlx)
- Add machine persistence across server restarts
- Add audit logging for session/viewer events
- Support codes now persisted to database

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

server/migrations/001_initial_schema.sql

@@ -0,0 +1,88 @@
+-- GuruConnect Initial Schema
+-- Machine persistence, session audit logging, and support codes
+
+-- Enable UUID generation
+CREATE EXTENSION IF NOT EXISTS "pgcrypto";
+
+-- Machines table - persistent agent records that survive server restarts
+CREATE TABLE connect_machines (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    agent_id VARCHAR(255) UNIQUE NOT NULL,
+    hostname VARCHAR(255) NOT NULL,
+    os_version VARCHAR(255),
+    is_elevated BOOLEAN DEFAULT FALSE,
+    is_persistent BOOLEAN DEFAULT TRUE,
+    first_seen TIMESTAMPTZ DEFAULT NOW(),
+    last_seen TIMESTAMPTZ DEFAULT NOW(),
+    last_session_id UUID,
+    status VARCHAR(20) DEFAULT 'offline',
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+CREATE INDEX idx_connect_machines_agent_id ON connect_machines(agent_id);
+CREATE INDEX idx_connect_machines_status ON connect_machines(status);
+
+-- Sessions table - connection history
+CREATE TABLE connect_sessions (
+    id UUID PRIMARY KEY,
+    machine_id UUID REFERENCES connect_machines(id) ON DELETE CASCADE,
+    started_at TIMESTAMPTZ DEFAULT NOW(),
+    ended_at TIMESTAMPTZ,
+    duration_secs INTEGER,
+    is_support_session BOOLEAN DEFAULT FALSE,
+    support_code VARCHAR(10),
+    status VARCHAR(20) DEFAULT 'active'
+);
+
+CREATE INDEX idx_connect_sessions_machine ON connect_sessions(machine_id);
+CREATE INDEX idx_connect_sessions_started ON connect_sessions(started_at DESC);
+CREATE INDEX idx_connect_sessions_support_code ON connect_sessions(support_code);
+
+-- Session events - comprehensive audit log
+CREATE TABLE connect_session_events (
+    id BIGSERIAL PRIMARY KEY,
+    session_id UUID REFERENCES connect_sessions(id) ON DELETE CASCADE,
+    event_type VARCHAR(50) NOT NULL,
+    timestamp TIMESTAMPTZ DEFAULT NOW(),
+    viewer_id VARCHAR(255),
+    viewer_name VARCHAR(255),
+    details JSONB,
+    ip_address INET
+);
+
+CREATE INDEX idx_connect_events_session ON connect_session_events(session_id);
+CREATE INDEX idx_connect_events_time ON connect_session_events(timestamp DESC);
+CREATE INDEX idx_connect_events_type ON connect_session_events(event_type);
+
+-- Support codes - persistent across restarts
+CREATE TABLE connect_support_codes (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    code VARCHAR(10) UNIQUE NOT NULL,
+    session_id UUID,
+    created_by VARCHAR(255) NOT NULL,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    expires_at TIMESTAMPTZ,
+    status VARCHAR(20) DEFAULT 'pending',
+    client_name VARCHAR(255),
+    client_machine VARCHAR(255),
+    connected_at TIMESTAMPTZ
+);
+
+CREATE INDEX idx_support_codes_code ON connect_support_codes(code);
+CREATE INDEX idx_support_codes_status ON connect_support_codes(status);
+CREATE INDEX idx_support_codes_session ON connect_support_codes(session_id);
+
+-- Trigger to auto-update updated_at on machines
+CREATE OR REPLACE FUNCTION update_connect_updated_at()
+RETURNS TRIGGER AS $$
+BEGIN
+    NEW.updated_at = NOW();
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER update_connect_machines_updated_at
+    BEFORE UPDATE ON connect_machines
+    FOR EACH ROW
+    EXECUTE FUNCTION update_connect_updated_at();