feat: enforce clippy warnings as errors in CI (#350)

[iam-mercy]

closes #350

This PR adds strict clippy linting enforcement to CI pipelines to address issue #350. All clippy warnings will now be treated as errors and fail the build, preventing code quality degradation.

Changes Made

1. CI Workflow Updates (.github/workflows/ci.yml)

Before:
```bash
cargo clippy
```

After:
```bash
cargo clippy --all-targets --all-features -- -D warnings
```

• Added `--all-targets` flag to lint all code (lib, tests, examples, benches)
• Added `--all-features` flag to enable all feature flags during linting
• Added `-- -D warnings` to treat all warnings as errors

2. Contract Tests Workflow Updates (.github/workflows/contract-tests.yml)

• Added `clippy` component to Rust toolchain installation
• Added dedicated clippy step before running tests:
  ```bash
  cargo clippy --all-targets --features testutils -- -D warnings
  ```
• Runs on ticket contract with testutils features enabled

3. Documentation (.docs/clippy-enforcement.md)

Comprehensive documentation covering:

• How clippy enforcement works in CI
• Local development workflow
• Common clippy warnings and fixes
• Configuration options
• Best practices and IDE integration
• Troubleshooting guide

Benefits

✅ Prevents Code Quality Degradation: Warnings caught before merge
✅ Consistency: Same standards enforced for all contributors
✅ Early Detection: Issues found in CI rather than code review
✅ Automated: No manual checking required
✅ Comprehensive: Lints all targets including tests and examples

Impact

Breaking Changes

⚠️ Existing warnings will now fail CI

If there are any existing clippy warnings in the codebase, they will need to be fixed before this PR can merge. To check:

```bash

Check explorer contract

cargo clippy --all-targets --all-features -- -D warnings

Check ticket contract

cd contracts/ticket
cargo clippy --all-targets --features testutils -- -D warnings
```

CI Workflow Changes

• Clippy now runs as a separate, distinct step
• Failures are clearly attributed to clippy issues
• Build fails fast on lint errors before running tests

Testing

Local Testing

Tested locally with:
```bash
cargo clippy --all-targets --all-features -- -D warnings
```

CI Testing

Once merged, CI will:

1. ✅ Checkout code
2. ✅ Setup Rust with clippy component
3. ✅ Run clippy with strict settings
4. ❌ Fail if any warnings found
5. ✅ Continue to tests only if clippy passes

Developer Experience

Before Committing

Developers should run locally:
```bash
cargo clippy --all-targets --all-features -- -D warnings
```

IDE Integration

Configure your IDE to run clippy on save:

• VS Code: rust-analyzer with "Check On Save: clippy"
• IntelliJ: Enable "Run clippy on save"
• Vim/Neovim: ALE or coc-rust-analyzer

Fixing Issues

Most clippy issues can be auto-fixed:
```bash
cargo clippy --fix --all-targets --all-features -- -D warnings
```

Rollout Plan

1. Phase 1: Fix any existing warnings in the codebase (if needed)
2. Phase 2: Merge this PR to enable enforcement
3. Phase 3: Monitor first few PRs to ensure smooth adoption
4. Phase 4: Update CONTRIBUTING.md with clippy requirements

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[Sundayabel222]

fix conflict @iam-mercy

[maztah1]

Conflicts Resolved ✅

Updated the PR to resolve all merge conflicts:

Changes Made

1. Rebased on latest main - No more conflicts with deleted contract-tests.yml
2. Enhanced clippy enforcement - Added --all-targets --all-features flags for comprehensive linting
3. Added documentation - Comprehensive docs/clippy-enforcement.md with:
   • Local development workflow
   • IDE integration guides
   • Common warnings and fixes
   • Troubleshooting section

What Changed in CI

\\yaml

Before

cargo clippy -- -D warnings

After

cargo clippy --all-targets --all-features -- -D warnings
\\

The --all-targets flag ensures clippy checks:

• Library code
• Binary targets
• Tests
• Examples
• Benchmarks

The --all-features flag ensures all feature-gated code is linted.

Ready to Merge

• ✅ No conflicts
• ✅ Based on latest upstream/main
• ✅ CI checks running
• ✅ Comprehensive documentation added

This PR is now ready for review and merge!

[iam-mercy]

conflicts has been resolved @Sundayabel222