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/src/db/machines.rs

@@ -0,0 +1,118 @@
+//! Machine/Agent database operations
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use sqlx::PgPool;
+use uuid::Uuid;
+
+/// Machine record from database
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct Machine {
+    pub id: Uuid,
+    pub agent_id: String,
+    pub hostname: String,
+    pub os_version: Option<String>,
+    pub is_elevated: bool,
+    pub is_persistent: bool,
+    pub first_seen: DateTime<Utc>,
+    pub last_seen: DateTime<Utc>,
+    pub last_session_id: Option<Uuid>,
+    pub status: String,
+    pub created_at: DateTime<Utc>,
+    pub updated_at: DateTime<Utc>,
+}
+
+/// Get or create a machine by agent_id (upsert)
+pub async fn upsert_machine(
+    pool: &PgPool,
+    agent_id: &str,
+    hostname: &str,
+    is_persistent: bool,
+) -> Result<Machine, sqlx::Error> {
+    sqlx::query_as::<_, Machine>(
+        r#"
+        INSERT INTO connect_machines (agent_id, hostname, is_persistent, status, last_seen)
+        VALUES ($1, $2, $3, 'online', NOW())
+        ON CONFLICT (agent_id) DO UPDATE SET
+            hostname = EXCLUDED.hostname,
+            status = 'online',
+            last_seen = NOW()
+        RETURNING *
+        "#,
+    )
+    .bind(agent_id)
+    .bind(hostname)
+    .bind(is_persistent)
+    .fetch_one(pool)
+    .await
+}
+
+/// Update machine status and info
+pub async fn update_machine_status(
+    pool: &PgPool,
+    agent_id: &str,
+    status: &str,
+    os_version: Option<&str>,
+    is_elevated: bool,
+    session_id: Option<Uuid>,
+) -> Result<(), sqlx::Error> {
+    sqlx::query(
+        r#"
+        UPDATE connect_machines SET
+            status = $1,
+            os_version = COALESCE($2, os_version),
+            is_elevated = $3,
+            last_seen = NOW(),
+            last_session_id = COALESCE($4, last_session_id)
+        WHERE agent_id = $5
+        "#,
+    )
+    .bind(status)
+    .bind(os_version)
+    .bind(is_elevated)
+    .bind(session_id)
+    .bind(agent_id)
+    .execute(pool)
+    .await?;
+    Ok(())
+}
+
+/// Get all persistent machines (for restore on startup)
+pub async fn get_all_machines(pool: &PgPool) -> Result<Vec<Machine>, sqlx::Error> {
+    sqlx::query_as::<_, Machine>(
+        "SELECT * FROM connect_machines WHERE is_persistent = true ORDER BY hostname"
+    )
+    .fetch_all(pool)
+    .await
+}
+
+/// Get machine by agent_id
+pub async fn get_machine_by_agent_id(
+    pool: &PgPool,
+    agent_id: &str,
+) -> Result<Option<Machine>, sqlx::Error> {
+    sqlx::query_as::<_, Machine>(
+        "SELECT * FROM connect_machines WHERE agent_id = $1"
+    )
+    .bind(agent_id)
+    .fetch_optional(pool)
+    .await
+}
+
+/// Mark machine as offline
+pub async fn mark_machine_offline(pool: &PgPool, agent_id: &str) -> Result<(), sqlx::Error> {
+    sqlx::query("UPDATE connect_machines SET status = 'offline', last_seen = NOW() WHERE agent_id = $1")
+        .bind(agent_id)
+        .execute(pool)
+        .await?;
+    Ok(())
+}
+
+/// Delete a machine record
+pub async fn delete_machine(pool: &PgPool, agent_id: &str) -> Result<(), sqlx::Error> {
+    sqlx::query("DELETE FROM connect_machines WHERE agent_id = $1")
+        .bind(agent_id)
+        .execute(pool)
+        .await?;
+    Ok(())
+}