Add lazygit devcontainer feature

[Copilot]

Adds a lazygit devcontainer feature that installs the lazygit terminal UI for git from GitHub releases, following the established pattern in this repo.

Changes

• src/lazygit/devcontainer-feature.json — Feature metadata; exposes a version option (default: latest)
• src/lazygit/install.sh — Downloads and installs the lazygit binary from jesseduffield/lazygit GitHub releases; maps Debian arch (amd64→x86_64, arm64→arm64, armhf→armv6, i386→x86) to match lazygit's release naming convention (lazygit_{version}_Linux_{arch}.tar.gz)
• test/lazygit/test.sh — Validates lazygit --version runs successfully
• .github/workflows/test.yaml — Adds lazygit to both test-autogenerated and test-scenarios CI matrices

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add lazygit feature</issue_title>
<issue_description>build on implementation in #104 </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add lazygit feature #107

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[sebst]

tests failing

[Copilot]

tests failing

Fixed in f41478a. Two issues were causing the test failures:

1. Test assertion (test/lazygit/test.sh): lazygit --version outputs commit=..., version=x.x.x, os=..., arch=... — it doesn't include the word "lazygit". Changed the grep from grep 'lazygit' to grep 'version='.

2. readonly variable error (install.sh): github_get_tag_for_version used local version="$2", which conflicted with the readonly version set earlier in install(). Renamed the local to ver to eliminate the naming clash.