fix(cargo): preserve clippy -- separator with cargo flags

[TechWizard9999]

Description

Fixes rtk cargo clippy argument reconstruction when cargo flags are present before --.

Related Issue

Closes #660

Changes Made

• hardened -- restoration logic to reconstruct the split point using ordered token matching (instead of broad containment counting)
• kept idempotent behavior when Clap already preserves --
• added regression tests for reported failing variants:
  • --all-targets -- -D warnings
  • --workspace -- -D warnings
• updated changelog under Unreleased bug fixes

Files Changed

• src/cargo_cmd.rs
• CHANGELOG.md

Testing

• cargo fmt --all --check
• rtk cargo clippy --all-targets (2 pre-existing warnings in untouched files)
• rtk cargo test
• rtk cargo test cargo_cmd::tests::test_restore_double_dash_clippy_with_all_targets
• rtk cargo test cargo_cmd::tests::test_restore_double_dash_clippy_with_workspace

cc @pszymkowiak for review

[CLAassistant]

All committers have signed the CLA.

[TechWizard9999]

@pszymkowiak could you please review this and let me know if anything needs to change?

[aeppling]

Hey

We are cleaning up the codebase and improving the project structure for better onboarding. As part of this effort, PR #826 reorganizes src/ from a flat layout into subfolders.

No logic changes — only file moves and import path updates.

What you need to do

Rebase your branch on develop when receiving this comment:

git fetch origin && git rebase origin/develop

Git detects renames automatically. If you get import conflicts, update the paths:

use crate::git;        // now: use crate::cmds::git::git;
use crate::tracking;   // now: use crate::core::tracking;
use crate::config;     // now: use crate::core::config;
use crate::init;       // now: use crate::hooks::init;
use crate::gain;       // now: use crate::analytics::gain;

Need help rebasing? Tag @aeppling

[TechWizard9999]

Rebased on latest develop per the refactor notice and force-updated this branch.

@pszymkowiak could you please re-review when convenient?

[TechWizard9999]

Rebased on latest develop and force-pushed to refresh this PR.\n\nI also re-ran the related cargo separator test locally.\n\n@pszymkowiak @FlorianBruniaux please re-review when convenient.

[TechWizard9999]

Quick maintainer ping after rebase/refresh. @pszymkowiak @FlorianBruniaux please re-review when convenient.