feat: Significant compilation improvements - reduced errors from 371 to 86

Major achievements:
- ✅ Implemented all missing SQLx traits for core types (OrderStatus, OrderSide, OrderType)
- ✅ Fixed Order struct with avg_fill_price field for database compatibility
- ✅ Resolved HashMap SQLx issues by using serde_json::Value
- ✅ Added comprehensive Exchange enum with 22+ exchanges and SQLx support
- ✅ Fixed MarketRegime SQLx implementations with Custom variant handling
- ✅ Implemented SQLx traits for OrderId and HftTimestamp
- ✅ Fixed Symbol, TimeInForce SQLx implementations
- ✅ Resolved module structure and brace mismatch issues

Current status:
- Errors reduced: 371 → 86 (77% reduction)
- 7 crates checking, 4 still have compilation issues
- Main remaining issues: type conversions and minor field mappings

Key files modified:
- common/src/types.rs: Added all SQLx implementations
- trading-data/: Fixed struct field mismatches
- common/src/lib.rs: Fixed re-exports

🤖 Generated with Claude Code

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

common/src/lib.rs

@@ -33,6 +33,10 @@ pub mod types;
 // Re-export all types at crate root for easy access
 pub use types::*;
 
+// Re-export trading types at crate root for easy access
+pub use trading::{TickType, BookAction, Side};
+pub use types::MarketRegime;
+
 // Re-export error types at crate root for direct access
 pub use error::{CommonError, CommonResult, ErrorCategory, RetryStrategy};
 
@@ -41,7 +45,7 @@ pub use error::{CommonError, CommonResult, ErrorCategory, RetryStrategy};
 mod sqlx_test;
 
 #[cfg(feature = "database")]
-mod sqlx_identifier_impls;
+
 
 pub mod prelude {
     //! Common types and utilities for Foxhunt services