Add structured logging, navigation bar, and code cleanup

## Backend
- Add Pino logging framework with timestamps and structured output
- Replace all console.error statements (49+) with proper logging levels
- Fix Drizzle ORM bug: replace invalid .get() calls with .limit(1)
- Remove unused auth routes file (already in index.js)
- Make internal functions private (remove unnecessary exports)
- Simplify code by removing excessive debug logging

## Frontend
- Add navigation bar to layout with:
  - User's callsign display
  - Navigation links (Dashboard, QSOs, Settings)
  - Logout button with red color distinction
- Navigation only shows when user is logged in
- Dark themed design matching footer

## Documentation
- Update README.md with new project structure
- Update docs/DOCUMENTATION.md with logging and nav bar info
- Add logger.js to configuration section

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/backend/services/auth.service.js

@@ -10,7 +10,7 @@ const SALT_ROUNDS = 10;
  * @param {string} password - Plain text password
  * @returns {Promise<string>} Hashed password
  */
-export async function hashPassword(password) {
+async function hashPassword(password) {
   return bcrypt.hash(password, SALT_ROUNDS);
 }
 
@@ -20,7 +20,7 @@ export async function hashPassword(password) {
  * @param {string} hash - Hashed password
  * @returns {Promise<boolean>} True if password matches
  */
-export async function verifyPassword(password, hash) {
+async function verifyPassword(password, hash) {
   return bcrypt.compare(password, hash);
 }
 
@@ -35,11 +35,11 @@ export async function verifyPassword(password, hash) {
  */
 export async function registerUser({ email, password, callsign }) {
   // Check if user already exists
-  const existingUser = await db
+  const [existingUser] = await db
     .select()
     .from(users)
     .where(eq(users.email, email))
-    .get();
+    .limit(1);
 
   if (existingUser) {
     throw new Error('Email already registered');
@@ -72,11 +72,11 @@ export async function registerUser({ email, password, callsign }) {
  */
 export async function authenticateUser(email, password) {
   // Find user by email
-  const user = await db
+  const [user] = await db
     .select()
     .from(users)
     .where(eq(users.email, email))
-    .get();
+    .limit(1);
 
   if (!user) {
     throw new Error('Invalid email or password');
@@ -99,11 +99,11 @@ export async function authenticateUser(email, password) {
  * @returns {Promise<Object|null>} User object (without password) or null
  */
 export async function getUserById(userId) {
-  const user = await db
+  const [user] = await db
     .select()
     .from(users)
     .where(eq(users.id, userId))
-    .get();
+    .limit(1);
 
   if (!user) return null;