feat(tli): Implement agent allocate-portfolio command (WAVE 12.3.3)

- Add AllocatePortfolioArgs struct with validation
- Support 5 allocation strategies (equal-weight, risk-parity, ml-optimized, mean-variance, kelly)
- Implement constraint validation (0 < min < max < 1.0, positive capital)
- Real gRPC integration with Trading Agent Service via API Gateway
- Formatted table output with portfolio allocations and risk metrics
- JWT authentication support via Bearer token in gRPC metadata
- 15 comprehensive TDD integration tests (all passing)
- Case-insensitive strategy parsing

Test Results: cargo test -p tli --test agent_commands_test
✅ 15 passed, 0 failed

Files:
- tli/src/commands/agent.rs (NEW - 466 lines)
- tli/src/commands/mod.rs (export AgentArgs)
- tli/src/main.rs (integrate agent command)
- tli/tests/agent_commands_test.rs (NEW - 15 tests)
- tli/proto/trading_agent.proto (NEW)

Co-authored-by: Wave 12.3.3 TDD Implementation

Cargo.lock

@@ -10228,6 +10228,8 @@ dependencies = [
  "prometheus",
  "prost 0.14.1",
  "prost-build",
+ "rust_decimal",
+ "rust_decimal_macros",
  "serde",
  "serde_json",
  "sqlx",