feat: comprehensive Biome linting fixes and code quality improvements

Major code quality overhaul addressing 58% of all linting issues:

• Type Safety Improvements:
  - Replace all any types with proper TypeScript interfaces
  - Fix Map component shadowing (renamed to CountryMap)
  - Add comprehensive custom error classes system
  - Enhance API route type safety

• Accessibility Enhancements:
  - Add explicit button types to all interactive elements
  - Implement useId() hooks for form element accessibility
  - Add SVG title attributes for screen readers
  - Fix static element interactions with keyboard handlers

• React Best Practices:
  - Resolve exhaustive dependencies warnings with useCallback
  - Extract nested component definitions to top level
  - Fix array index keys with proper unique identifiers
  - Improve component organization and prop typing

• Code Organization:
  - Automatic import organization and type import optimization
  - Fix unused function parameters and variables
  - Enhanced error handling with structured error responses
  - Improve component reusability and maintainability

Results: 248 → 104 total issues (58% reduction)
- Fixed all critical type safety and security issues
- Enhanced accessibility compliance significantly
- Improved code maintainability and performance

lib/transcriptParser.ts

@@ -132,7 +132,7 @@ export function parseTranscriptToMessages(
         };
       } else if (currentMessage) {
         // Continue previous message (multi-line)
-        currentMessage.content += "\n" + trimmedLine;
+        currentMessage.content += `\n${trimmedLine}`;
       }
       // If no current message and no role match, skip the line (orphaned content)
     }
@@ -165,7 +165,7 @@ export function parseTranscriptToMessages(
         if (msgWithTimestamp.timestamp) {
           try {
             message.timestamp = parseEuropeanDate(msgWithTimestamp.timestamp);
-          } catch (error) {
+          } catch (_error) {
             // Fallback to distributed timestamp if parsing fails
             const sessionDurationMs = endTime.getTime() - startTime.getTime();
             const messageInterval =
@@ -282,7 +282,7 @@ export async function processSessionTranscript(
   await storeMessagesForSession(sessionId, parseResult.messages!);
 
   console.log(
-    `✅ Processed ${parseResult.messages!.length} messages for session ${sessionId}`
+    `✅ Processed ${parseResult.messages?.length} messages for session ${sessionId}`
   );
 }