feat: Configure database with Prisma and MySQL spatial support (Task 22)

- Set up MySQL 8.0+ with spatial data support (POINT SRID 4326)
- Created Prisma schema with all models (User, Report, Event, etc.)
- Added Clerk authentication support (clerk_id field)
- Configured spatial indexes on location fields for performance
- Created database migrations and applied to MySQL
- Built spatial query utilities for geographical operations
- Added database connection singleton and health checks
- Created comprehensive documentation and test scripts

Requirements: 1.1, 2.1, 3.2, 4.1

server/prisma/migrations/20241116000001_add_clerk_auth/migration.sql

@@ -0,0 +1,13 @@
+-- AlterTable: Add clerk_id column and remove password_hash
+ALTER TABLE `users` ADD COLUMN `clerk_id` VARCHAR(255) NULL;
+
+-- Create unique index on clerk_id
+CREATE UNIQUE INDEX `clerk_id` ON `users`(`clerk_id`);
+
+-- Create index for clerk_id lookups
+CREATE INDEX `idx_clerk_id` ON `users`(`clerk_id`);
+
+-- Drop password_hash column (after data migration if needed)
+-- Note: In production, you would first migrate existing users to Clerk before dropping this column
+-- For now, we'll keep it to avoid data loss, but it should be removed after Clerk migration is complete
+-- ALTER TABLE `users` DROP COLUMN `password_hash`;