feat: file tree folding, hierarchy navigation, and combined directory diffs

[felipecm-br]

Summary

Hi @Blankeos and contributors! 👋

This PR enhances the file tree experience across lazygitrs by introducing explicit directory folding, rapid tree hierarchy traversal (parent/child/siblings), and direct combined folder diffs.

All new actions are fully customizable in config.yml and integrated with the Command Palette / Help popup and status bar.

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What's Changed & Key Advantages

1. Explicit Directory Folding (- by default):

   • Pressing - (customizable via keybinding.universal.foldDirectory) folds and unfolds the selected directory node, including the root node (/), without confusing it with selecting child files.

2. Combined Directory Diff Inspection (Enter on directories):

   • Pressing Enter on any directory node (or root /) focuses the diff view and displays a unified combined diff of all modified child files under that folder. This provides a great high-level overview of what changed in an entire module or directory before diving into individual files.

3. Fast Tree Hierarchy & Sibling Navigation (,, ., <, > by default):

   • , (parent - keybinding.universal.treeParent): Jumps straight up to the parent directory node.
   • . (first child - keybinding.universal.treeChild): Jumps into the first child node of the directory.
   • < (prev sibling - keybinding.universal.treePrevSibling): Jumps to the previous sibling node at the same tree depth.
   • > (next sibling - keybinding.universal.treeNextSibling): Jumps to the next sibling node at the same tree depth.
   • These keys also work seamlessly from within the focused diff view, allowing quick jumping between folder/file diffs without returning to the sidebar.

4. 100% Configurable & Dynamic UI:

   • Added foldDirectory, treeParent, treeChild, treePrevSibling, and treeNextSibling to UniversalKeybinding.
   • Users on non-US or alternative keyboard layouts (such as ABNT2, Dvorak, Colemak, etc.) can customize these keys in ~/.config/lazygit/config.yml under universal:

     keybinding:
       universal:
         foldDirectory: "-"
         treeParent: ","
         treeChild: "."
         treePrevSibling: "<"
         treeNextSibling: ">"

   • Command Palette (?) and bottom status bar dynamically reflect the active user configuration.
   • Added a conflict guard to ensure . does not accidentally toggle commit details when navigating commit file trees.

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Testing

• Added unit tests for tree hierarchy navigation algorithms (test_tree_navigation).
• Added unit tests for keybinding default values and YAML deserialization (test_tree_keybindings_defaults_and_deserialization).
• Verified all 146 tests pass (cargo test).
• Verified code formatting with cargo fmt.
• Tested interactively on multi-level nested working tree and commit file changes.

Thank you for creating and maintaining lazygitrs! Feedback and reviews are warmly welcomed.

[Blankeos]

All great PRs btw! I'll review them tonight, thanks so much!

[Blankeos]

Reviewed and locally retested the integrated file-tree changes and follow-up fixes. All 302 tests pass with cargo test --locked; cargo fmt --check, cargo build --locked, and git diff --check pass. Confirmed defaults: '.' selects the first visible child; apostrophe toggles Commit Details. Footers show only configured fold/unfold in active tree lists, with hierarchy navigation in contextual help. Navigation preserves viewport/diff refresh behavior and Enter preserves screen layout. Approved for squash merge following user retest.