Add debug logging and optimize SQLite performance

- Add debug logging for goroutines and memory usage (enabled via DEBUG=routewatch)
- Increase SQLite connection pool from 1 to 10 connections for better concurrency
- Optimize SQLite pragmas for balanced performance and safety
- Add proper shutdown handling for peering handler
- Define constants to avoid magic numbers in code

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

internal/database/database.go

@@ -30,6 +30,11 @@ const (
 	ipv4Offset     = 12
 	ipv4Bits       = 32
 	maxIPv4        = 0xFFFFFFFF
+
+	// Database connection pool settings
+	maxOpenConns    = 10
+	maxIdleConns    = 5
+	connMaxLifetime = 5 * time.Minute
 )
 
 // Common errors
@@ -73,10 +78,10 @@ func New(cfg *config.Config, logger *logger.Logger) (*Database, error) {
 	}
 
 	// Set connection pool parameters
-	// Single connection to avoid locking issues with SQLite
-	db.SetMaxOpenConns(1)
-	db.SetMaxIdleConns(1)
-	db.SetConnMaxLifetime(0)
+	// Allow multiple readers but single writer for SQLite WAL mode
+	db.SetMaxOpenConns(maxOpenConns)
+	db.SetMaxIdleConns(maxIdleConns)
+	db.SetConnMaxLifetime(connMaxLifetime)
 
 	database := &Database{db: db, logger: logger, path: dbPath}
 
@@ -89,19 +94,20 @@ func New(cfg *config.Config, logger *logger.Logger) (*Database, error) {
 
 // Initialize creates the database schema if it doesn't exist.
 func (d *Database) Initialize() error {
-	// Set SQLite pragmas for better performance
-	// WARNING: These settings trade durability for speed
+	// Set SQLite pragmas for better performance with safety
 	pragmas := []string{
-		"PRAGMA journal_mode=WAL",         // Write-Ahead Logging
-		"PRAGMA synchronous=OFF",          // Don't wait for disk writes - RISKY but FAST
-		"PRAGMA cache_size=-1048576",      // 1GB cache (negative = KB)
-		"PRAGMA temp_store=MEMORY",        // Use memory for temp tables
-		"PRAGMA mmap_size=536870912",      // 512MB memory-mapped I/O
-		"PRAGMA wal_autocheckpoint=10000", // Checkpoint every 10000 pages (less frequent)
-		"PRAGMA wal_checkpoint(PASSIVE)",  // Checkpoint now
-		"PRAGMA page_size=8192",           // Larger page size for better performance
-		"PRAGMA busy_timeout=30000",       // 30 second busy timeout
-		"PRAGMA optimize",                 // Run optimizer
+		"PRAGMA journal_mode=WAL",        // Write-Ahead Logging
+		"PRAGMA synchronous=NORMAL",      // Balance between safety and speed
+		"PRAGMA cache_size=-262144",      // 256MB cache (negative = KB)
+		"PRAGMA temp_store=MEMORY",       // Use memory for temp tables
+		"PRAGMA mmap_size=268435456",     // 256MB memory-mapped I/O
+		"PRAGMA wal_autocheckpoint=1000", // Checkpoint every 1000 pages
+		"PRAGMA wal_checkpoint(PASSIVE)", // Checkpoint now
+		"PRAGMA page_size=4096",          // Standard page size
+		"PRAGMA busy_timeout=30000",      // 30 second busy timeout
+		"PRAGMA optimize",                // Run optimizer
+		"PRAGMA locking_mode=NORMAL",     // Allow multiple connections
+		"PRAGMA read_uncommitted=true",   // Allow dirty reads for better concurrency
 	}
 
 	for _, pragma := range pragmas {