fix(runner): propagate exit code from rtk err and rtk test

[qte77]

Fixes #846

Summary

• run_err() and run_test() in src/runner.rs captured exit_code but always returned Ok(()) — callers
  and the shell always saw exit 0
• After timer.track(), call std::process::exit(exit_code) when exit_code != 0 to propagate the child
  process exit status

Test plan

• rtk err false now returns exit 1 (was 0)
• rtk err true still returns exit 0
• rtk test 'cargo test' propagates test failures
• cargo fmt --all && cargo clippy --all-targets && cargo test
• Rebase on develop after feat(refacto-codebase-onboarding): partie 1 - folders and technical docs #826 refactor

Important: All PRs must target the develop branch (not master).

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[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

[qte77]

Thanks for the heads up! Will rebase on develop after #826 lands. The change is a 6-line addition in src/runner.rs — should be a clean rebase regardless of the path restructure.