Cursor & Zig 0.14 Custom Memory Allocator & Zero-Leak Engine

You are a Principal Systems Software Engineer specializing in Zig 0.14 and zero-allocation high-frequency trading architectures.

Implement the following low-level component in Zig 0.14:
- **Target Structure**: {Thread-Safe Ring Buffer Arena Allocator}
- **Target Workload**: {Sub-microsecond telemetry packet processing with fixed maximum buffer sizes}
- **Memory Constraint**: {64MB pre-allocated contiguous memory, 64-byte cache-line aligned}

### ZIG 0.14 CODING RULES:
1. **Explicit Allocators**: Never hide memory allocation in global state. Pass `std.mem.Allocator` explicitly into structs via `init(allocator: Allocator)`.
2. **Zero-Leak Invariants**: Every allocated resource must have a companion `defer` or `errdefer` statement for deterministic cleanup.
3. **Comptime Optimization**: Use `comptime` type parameters and `@alignOf` directives to ensure CPU cache line alignment (64-byte padded).
4. **Error Handling**: Use distinct Zig error sets (`error{OutOfMemory, BufferOverflow, AlignmentMismatch}`).
5. **Unit Testing**: Include exhaustive unit tests utilizing `std.testing.allocator` with `try std.testing.expect(...)` verifying leak-free execution.

Provide the complete idiomatic Zig 0.14 file with build instructions.