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/sessions.rs

@@ -0,0 +1,98 @@
+//! Session database operations
+
+use chrono::{DateTime, Utc};
+use serde::{Deserialize, Serialize};
+use sqlx::PgPool;
+use uuid::Uuid;
+
+/// Session record from database
+#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
+pub struct DbSession {
+    pub id: Uuid,
+    pub machine_id: Option<Uuid>,
+    pub started_at: DateTime<Utc>,
+    pub ended_at: Option<DateTime<Utc>>,
+    pub duration_secs: Option<i32>,
+    pub is_support_session: bool,
+    pub support_code: Option<String>,
+    pub status: String,
+}
+
+/// Create a new session record
+pub async fn create_session(
+    pool: &PgPool,
+    session_id: Uuid,
+    machine_id: Uuid,
+    is_support_session: bool,
+    support_code: Option<&str>,
+) -> Result<DbSession, sqlx::Error> {
+    sqlx::query_as::<_, DbSession>(
+        r#"
+        INSERT INTO connect_sessions (id, machine_id, is_support_session, support_code, status)
+        VALUES ($1, $2, $3, $4, 'active')
+        RETURNING *
+        "#,
+    )
+    .bind(session_id)
+    .bind(machine_id)
+    .bind(is_support_session)
+    .bind(support_code)
+    .fetch_one(pool)
+    .await
+}
+
+/// End a session
+pub async fn end_session(
+    pool: &PgPool,
+    session_id: Uuid,
+    status: &str,  // 'ended' or 'disconnected' or 'timeout'
+) -> Result<(), sqlx::Error> {
+    sqlx::query(
+        r#"
+        UPDATE connect_sessions SET
+            ended_at = NOW(),
+            duration_secs = EXTRACT(EPOCH FROM (NOW() - started_at))::INTEGER,
+            status = $1
+        WHERE id = $2
+        "#,
+    )
+    .bind(status)
+    .bind(session_id)
+    .execute(pool)
+    .await?;
+    Ok(())
+}
+
+/// Get session by ID
+pub async fn get_session(pool: &PgPool, session_id: Uuid) -> Result<Option<DbSession>, sqlx::Error> {
+    sqlx::query_as::<_, DbSession>("SELECT * FROM connect_sessions WHERE id = $1")
+        .bind(session_id)
+        .fetch_optional(pool)
+        .await
+}
+
+/// Get active sessions for a machine
+pub async fn get_active_sessions_for_machine(
+    pool: &PgPool,
+    machine_id: Uuid,
+) -> Result<Vec<DbSession>, sqlx::Error> {
+    sqlx::query_as::<_, DbSession>(
+        "SELECT * FROM connect_sessions WHERE machine_id = $1 AND status = 'active' ORDER BY started_at DESC"
+    )
+    .bind(machine_id)
+    .fetch_all(pool)
+    .await
+}
+
+/// Get recent sessions (for dashboard)
+pub async fn get_recent_sessions(
+    pool: &PgPool,
+    limit: i64,
+) -> Result<Vec<DbSession>, sqlx::Error> {
+    sqlx::query_as::<_, DbSession>(
+        "SELECT * FROM connect_sessions ORDER BY started_at DESC LIMIT $1"
+    )
+    .bind(limit)
+    .fetch_all(pool)
+    .await
+}