Move documentation to docs/ directory and improve terminology

- Move ARCHITECTURE.md and CLAUDE.md to docs/ directory
- Replace "real-time" terminology with accurate "low-latency" and "high-performance"
- Update README to reflect correct performance characteristics
- Add comprehensive ICAO country database with SQLite backend
- Fix display options positioning and functionality
- Add map scale controls and improved range ring visibility
- Enhance aircraft marker orientation and trail management

🤖 Generated with [Claude Code](https://claude.ai/code)

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

internal/icao/database.go

@@ -0,0 +1,119 @@
+package icao
+
+import (
+	"database/sql"
+	"embed"
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+//go:embed icao.db
+var icaoFS embed.FS
+
+// Database handles ICAO address to country lookups
+type Database struct {
+	db *sql.DB
+}
+
+// CountryInfo represents country information for an aircraft
+type CountryInfo struct {
+	Country     string `json:"country"`
+	CountryCode string `json:"country_code"`
+	Flag        string `json:"flag"`
+}
+
+// NewDatabase creates a new ICAO database connection
+func NewDatabase() (*Database, error) {
+	// Extract embedded database to a temporary file
+	data, err := icaoFS.ReadFile("icao.db")
+	if err != nil {
+		return nil, fmt.Errorf("failed to read embedded ICAO database: %w", err)
+	}
+
+	// Create temporary file for the database
+	tmpFile, err := os.CreateTemp("", "icao-*.db")
+	if err != nil {
+		return nil, fmt.Errorf("failed to create temporary file: %w", err)
+	}
+	tmpPath := tmpFile.Name()
+
+	// Write database data to temporary file
+	if _, err := io.WriteString(tmpFile, string(data)); err != nil {
+		tmpFile.Close()
+		os.Remove(tmpPath)
+		return nil, fmt.Errorf("failed to write database to temp file: %w", err)
+	}
+	tmpFile.Close()
+
+	// Open SQLite database
+	db, err := sql.Open("sqlite3", tmpPath+"?mode=ro") // Read-only mode
+	if err != nil {
+		os.Remove(tmpPath)
+		return nil, fmt.Errorf("failed to open SQLite database: %w", err)
+	}
+
+	// Test the database connection
+	if err := db.Ping(); err != nil {
+		db.Close()
+		os.Remove(tmpPath)
+		return nil, fmt.Errorf("failed to ping database: %w", err)
+	}
+
+	return &Database{db: db}, nil
+}
+
+// LookupCountry returns country information for an ICAO address
+func (d *Database) LookupCountry(icaoHex string) (*CountryInfo, error) {
+	if len(icaoHex) != 6 {
+		return &CountryInfo{
+			Country:     "Unknown",
+			CountryCode: "XX",
+			Flag:        "🏳️",
+		}, nil
+	}
+
+	// Convert hex string to integer
+	icaoInt, err := strconv.ParseInt(icaoHex, 16, 64)
+	if err != nil {
+		return &CountryInfo{
+			Country:     "Unknown",
+			CountryCode: "XX",
+			Flag:        "🏳️",
+		}, nil
+	}
+
+	var country, countryCode, flag string
+	query := `
+		SELECT country, country_code, flag 
+		FROM icao_allocations 
+		WHERE ? BETWEEN start_addr AND end_addr 
+		LIMIT 1
+	`
+
+	err = d.db.QueryRow(query, icaoInt).Scan(&country, &countryCode, &flag)
+	if err != nil {
+		if err == sql.ErrNoRows {
+			return &CountryInfo{
+				Country:     "Unknown",
+				CountryCode: "XX",
+				Flag:        "🏳️",
+			}, nil
+		}
+		return nil, fmt.Errorf("database query failed: %w", err)
+	}
+
+	return &CountryInfo{
+		Country:     country,
+		CountryCode: countryCode,
+		Flag:        flag,
+	}, nil
+}
+
+// Close closes the database connection
+func (d *Database) Close() error {
+	return d.db.Close()
+}