Add a history list key context to the Git panel (#63689)

# Objective

The Git Panel exposes the `ChangesList` key context while its list is
focused, including when the History tab is active. This causes
Changes-only keybindings to match in History and provides no context for
History-specific bindings.

This is a fresh submission of the revised change from #63669, as
requested in that PR's discussion.

Fixes #61012

## Solution

Select the list key context from the active Git Panel tab. Changes
exposes `ChangesList`, while History exposes `HistoryList`. The shared
`GitPanel` and `menu` contexts remain unchanged.

Preserve compatible keyboard behavior by sharing navigation,
confirmation, and cancellation bindings between `ChangesList` and
`HistoryList` on macOS, Linux, Windows, and Vim. File, staging, restore,
and commit-editor bindings remain exclusive to `ChangesList`.

Extend the dispatch-context test to verify that the list contexts are
mutually exclusive and absent while the commit editor is focused.

## Testing

- `cargo fmt --package git_ui -- --check`
- `./script/check-keymaps`
- `git diff --check`
- `cargo test -p git_ui test_dispatch_context_with_focus_states --
--nocapture`
- `cargo test -p git_ui` (153 passed)
- `cargo build -p zed`
- Manually verified on macOS that History reports `HistoryList` without
`ChangesList`, arrow navigation selects commits, and Enter opens the
selected commit
- Linux and Windows keymaps were updated and checked, but not manually
exercised on those platforms

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

## Showcase

The Keyboard Context view shows `GitPanel`, `menu`, and `HistoryList`
while the History tab is focused. `ChangesList` is absent.

![Keyboard Context view showing the HistoryList
context](https://github.com/user-attachments/assets/63422131-b16d-4d30-997c-17aec7924011)

---

Release Notes:

- Fixed Git Panel keybindings matching the Changes tab while the History
tab is active.

assets/keymaps/default-linux.json

@@ -1035,6 +1035,17 @@
       "ctrl-2": "git_panel::ActivateHistoryTab",
     },
   },
+  {
+    "context": "GitPanel && (ChangesList || HistoryList) && !GitBranchSelector && !GitRepositorySelector",
+    "bindings": {
+      "up": "menu::SelectPrevious",
+      "down": "menu::SelectNext",
+      "shift-up": "menu::SelectPrevious",
+      "shift-down": "menu::SelectNext",
+      "enter": "menu::Confirm",
+      "escape": "menu::Cancel",
+    },
+  },
   {
     "context": "GitPanel && ChangesList && !GitBranchSelector && !GitRepositorySelector",
     "bindings": {
@@ -1042,9 +1053,6 @@
       "right": "git_panel::ExpandSelectedEntry",
       "up": "git_panel::PreviousEntry",
       "down": "git_panel::NextEntry",
-      "shift-up": "menu::SelectPrevious",
-      "shift-down": "menu::SelectNext",
-      "enter": "menu::Confirm",
       "alt-y": "git::StageFile",
       "alt-shift-y": "git::UnstageFile",
       "ctrl-alt-y": "git::ToggleStaged",
@@ -1056,7 +1064,6 @@
       "alt-ctrl-shift-c": "workspace::CopyRelativePath",
       "tab": "git_panel::FocusEditor",
       "shift-tab": "git_panel::FocusEditor",
-      "escape": "menu::Cancel",
       "alt-enter": "menu::SecondaryConfirm",
       "delete": ["git::RestoreFile", { "skip_prompt": false }],
       "backspace": ["git::RestoreFile", { "skip_prompt": false }],

assets/keymaps/default-macos.json

@@ -1094,19 +1094,28 @@
       "cmd-2": "git_panel::ActivateHistoryTab",
     },
   },
+  {
+    "context": "GitPanel && (ChangesList || HistoryList) && !GitBranchSelector && !GitRepositorySelector",
+    "use_key_equivalents": true,
+    "bindings": {
+      "up": "menu::SelectPrevious",
+      "down": "menu::SelectNext",
+      "shift-up": "menu::SelectPrevious",
+      "shift-down": "menu::SelectNext",
+      "enter": "menu::Confirm",
+      "escape": "menu::Cancel",
+    },
+  },
   {
     "context": "GitPanel && ChangesList && !GitBranchSelector && !GitRepositorySelector",
     "use_key_equivalents": true,
     "bindings": {
       "up": "git_panel::PreviousEntry",
       "down": "git_panel::NextEntry",
-      "shift-up": "menu::SelectPrevious",
-      "shift-down": "menu::SelectNext",
       "cmd-up": "git_panel::FirstEntry",
       "cmd-down": "git_panel::LastEntry",
       "left": "git_panel::CollapseSelectedEntry",
       "right": "git_panel::ExpandSelectedEntry",
-      "enter": "menu::Confirm",
       "cmd-alt-y": "git::ToggleStaged",
       "space": "git::ToggleStaged",
       "shift-space": "git::StageRange",
@@ -1117,7 +1126,6 @@
       "alt-down": "git_panel::FocusEditor",
       "tab": "git_panel::FocusEditor",
       "shift-tab": "git_panel::FocusEditor",
-      "escape": "menu::Cancel",
       "backspace": ["git::RestoreFile", { "skip_prompt": false }],
       "delete": ["git::RestoreFile", { "skip_prompt": false }],
       "cmd-backspace": ["git::RestoreFile", { "skip_prompt": true }],

assets/keymaps/default-windows.json

@@ -1028,17 +1028,26 @@
       "ctrl-2": "git_panel::ActivateHistoryTab",
     },
   },
+  {
+    "context": "GitPanel && (ChangesList || HistoryList) && !GitBranchSelector && !GitRepositorySelector",
+    "use_key_equivalents": true,
+    "bindings": {
+      "up": "menu::SelectPrevious",
+      "down": "menu::SelectNext",
+      "shift-up": "menu::SelectPrevious",
+      "shift-down": "menu::SelectNext",
+      "enter": "menu::Confirm",
+      "escape": "menu::Cancel",
+    },
+  },
   {
     "context": "GitPanel && ChangesList && !GitBranchSelector && !GitRepositorySelector",
     "use_key_equivalents": true,
     "bindings": {
       "up": "git_panel::PreviousEntry",
       "down": "git_panel::NextEntry",
-      "shift-up": "menu::SelectPrevious",
-      "shift-down": "menu::SelectNext",
       "left": "git_panel::CollapseSelectedEntry",
       "right": "git_panel::ExpandSelectedEntry",
-      "enter": "menu::Confirm",
       "alt-y": "git::StageFile",
       "shift-alt-y": "git::UnstageFile",
       "space": "git::ToggleStaged",
@@ -1047,7 +1056,6 @@
       "ctrl-k ctrl-shift-c": "workspace::CopyRelativePath",
       "tab": "git_panel::FocusEditor",
       "shift-tab": "git_panel::FocusEditor",
-      "escape": "menu::Cancel",
       "alt-enter": "menu::SecondaryConfirm",
       "delete": ["git::RestoreFile", { "skip_prompt": false }],
       "backspace": ["git::RestoreFile", { "skip_prompt": false }],

assets/keymaps/vim.json

@@ -1123,17 +1123,23 @@
       "g g": "menu::SelectFirst",
     },
   },
+  {
+    "context": "GitPanel && (ChangesList || HistoryList) && !GitBranchSelector && !GitRepositorySelector",
+    "use_key_equivalents": true,
+    "bindings": {
+      "j": "menu::SelectNext",
+      "k": "menu::SelectPrevious",
+      "g f": "menu::Confirm",
+    },
+  },
   {
     "context": "GitPanel && ChangesList && !GitBranchSelector && !GitRepositorySelector",
     "use_key_equivalents": true,
     "bindings": {
       "h": "git_panel::CollapseSelectedEntry",
-      "j": "menu::SelectNext",
-      "k": "menu::SelectPrevious",
       "l": "git_panel::ExpandSelectedEntry",
       "g g": "menu::SelectFirst",
       "shift-g": "menu::SelectLast",
-      "g f": "menu::Confirm",
       "i": "git_panel::FocusEditor",
       "x": "git::ToggleStaged",
       "shift-x": "git::StageAll",