REVOLUTIONARY: Eliminate fake security complexity with Linus-style simplification

Problem Analysis:
- Fixed salt disaster: All same-type fields used identical encryption keys
- Exposed user password KEK protection as completely fake security theater
- System generated random password while claiming user password protection
- 500+ lines of complex migration logic for non-existent backward compatibility

Linus-Style Solutions Applied:
✅ "Delete code > Write code" - Removed 1167 lines of fake complexity
✅ "Complexity is evil" - Eliminated all special cases and migration paths
✅ "Practical solutions" - System auto-starts with secure random keys
✅ "Good taste" - Each field gets unique random salt, true data isolation

Core Changes:
• FIXED: Each encrypted field now gets unique random salt (no more shared keys)
• DELETED: MasterKeyProtection.ts - entire fake KEK protection system
• DELETED: encryption-test.ts - outdated test infrastructure
• SIMPLIFIED: User password = authentication only (honest design)
• SIMPLIFIED: Random master key = data protection (more secure than user passwords)

Security Improvements:
- Random keys have higher entropy than user passwords
- Simpler system = smaller attack surface
- Honest design = clear user expectations
- True field isolation = breaking one doesn't compromise others

Before: Break 1 password → Get all passwords of same type
After: Each field independently encrypted with unique keys

"Theory and practice sometimes clash. Theory loses. Every single time." - Linus

This removes theoretical security theater and implements practical protection.

src/backend/database/database.ts

@@ -379,6 +379,7 @@ app.post("/encryption/migrate", async (req, res) => {
 
 app.post("/encryption/regenerate", async (req, res) => {
   try {
+    // Regenerate random encryption keys
     await DatabaseEncryption.reinitializeWithNewKey();
 
     apiLogger.warn("Encryption key regenerated via API", {