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/mod.rs

@@ -1,45 +1,52 @@
-//! Database module
+//! Database module for GuruConnect
 //!
-//! Handles session logging and persistence.
-//! Optional for MVP - sessions are kept in memory only.
+//! Handles persistence for machines, sessions, and audit logging.
+//! Optional - server works without database if DATABASE_URL not set.
+
+pub mod machines;
+pub mod sessions;
+pub mod events;
+pub mod support_codes;
 
 use anyhow::Result;
+use sqlx::postgres::PgPoolOptions;
+use sqlx::PgPool;
+use tracing::info;
 
-/// Database connection pool (placeholder)
+pub use machines::*;
+pub use sessions::*;
+pub use events::*;
+pub use support_codes::*;
+
+/// Database connection pool wrapper
 #[derive(Clone)]
 pub struct Database {
-    // TODO: Add sqlx pool when PostgreSQL is needed
-    _placeholder: (),
+    pool: PgPool,
 }
 
 impl Database {
-    /// Initialize database connection
-    pub async fn init(_database_url: &str) -> Result<Self> {
-        // TODO: Initialize PostgreSQL connection pool
-        Ok(Self { _placeholder: () })
+    /// Initialize database connection pool
+    pub async fn connect(database_url: &str, max_connections: u32) -> Result<Self> {
+        info!("Connecting to database...");
+        let pool = PgPoolOptions::new()
+            .max_connections(max_connections)
+            .connect(database_url)
+            .await?;
+
+        info!("Database connection established");
+        Ok(Self { pool })
     }
-}
 
-/// Session event for audit logging
-#[derive(Debug)]
-pub struct SessionEvent {
-    pub session_id: String,
-    pub event_type: SessionEventType,
-    pub details: Option<String>,
-}
-
-#[derive(Debug)]
-pub enum SessionEventType {
-    Started,
-    ViewerJoined,
-    ViewerLeft,
-    Ended,
-}
-
-impl Database {
-    /// Log a session event (placeholder)
-    pub async fn log_session_event(&self, _event: SessionEvent) -> Result<()> {
-        // TODO: Insert into connect_session_events table
+    /// Run database migrations
+    pub async fn migrate(&self) -> Result<()> {
+        info!("Running database migrations...");
+        sqlx::migrate!("./migrations").run(&self.pool).await?;
+        info!("Migrations complete");
         Ok(())
     }
+
+    /// Get reference to the connection pool
+    pub fn pool(&self) -> &PgPool {
+        &self.pool
+    }
 }