fix(perps): bound solana funding velocity precision

[rndrntwrk]

Summary

• rejects Solana perps config updates that use EVM-scale funding velocity literals
• preserves the current keeper-scale default path while bounding raw Solana funding velocity to the program precision domain
• adds Rust unit coverage and an Anchor integration assertion for the rejected config update

Validation

• cargo test -p gold_perps_market config_rejects_evm_scale_funding_velocity -- --nocapture
• cargo test -p gold_perps_market
• anchor build -p gold_perps_market
• git diff --check

Note

anchor test -p gold_perps_market --run tests/gold_perps_market.ts still fails before reaching this branch's new integration assertion because the existing local harness initializes program_data with an upgrade authority that does not match ensurePerpsConfig's initializer. That is a test-harness bootstrap issue, not a regression from this patch.