Add custom logger with source location tracking and remove verbose database logs

- Create internal/logger package with Logger wrapper around slog
- Logger automatically adds source file, line number, and function name to all log entries
- Use golang.org/x/term to properly detect if stdout is a terminal
- Replace all slog.Logger usage with logger.Logger throughout the codebase
- Remove verbose logging from database GetStats() method
- Update all constructors and dependencies to use the new logger

internal/routewatch/peerhandler.go

@@ -1,10 +1,10 @@
 package routewatch
 
 import (
-	"log/slog"
 	"strconv"
 
 	"git.eeqj.de/sneak/routewatch/internal/database"
+	"git.eeqj.de/sneak/routewatch/internal/logger"
 	"git.eeqj.de/sneak/routewatch/internal/ristypes"
 )
 
@@ -16,11 +16,11 @@ const (
 // PeerHandler tracks BGP peers from all message types
 type PeerHandler struct {
 	db     database.Store
-	logger *slog.Logger
+	logger *logger.Logger
 }
 
 // NewPeerHandler creates a new peer tracking handler
-func NewPeerHandler(db database.Store, logger *slog.Logger) *PeerHandler {
+func NewPeerHandler(db database.Store, logger *logger.Logger) *PeerHandler {
 	return &PeerHandler{
 		db:     db,
 		logger: logger,