chore(workspace): enforce clippy warnings and format workspace

[Bhanudahiyaa]

Summary

Enforces warning-level clippy gating and aligns workspace formatting/lint baseline so local and CI quality gates behave as intended.

Motivation

The previous clippy command used -D errors, which does not correctly deny warnings. This weakens lint enforcement and can hide actionable diagnostics. Additionally, workspace formatting drift caused cargo fmt --check failures.

Changes

• Updated clippy deny flag from -D errors to -D warnings in:
• .github/workflows/ci.yml
• CONTRIBUTING.md (all listed quality-gate/checklist command references)
• Fixed clippy warning in crates/mofa-foundation/src/llm/google.rs (collapsed nested if statements).
• Applied formatting updates required for cargo fmt --check to pass across the workspace.

Related Issues

Resolves #1301

Testing

cargo fmt --check
cargo clippy --workspace --all-features -- -D warnings
PYO3_PYTHON=/opt/homebrew/bin/python3.11 cargo test --workspace --all-features
cargo build --examples
cargo doc --workspace --no-deps --all-features

Checklist

• cargo fmt --check passes
• cargo clippy --workspace --all-features -- -D warnings passes
• cargo test --workspace --all-features passes
• cargo build --examples succeeds
• cargo doc --workspace --no-deps --all-features succeeds
• Architecture layer rules respected (see CONTRIBUTING.md)
• Relevant documentation updated