command_palette: Fix keymap editor not matching actions with underscored namespaces (#50415)

Closes https://github.com/zed-industries/zed/issues/50223

## Summary

When clicking **Change Keybinding** from the command palette on an
action whose namespace contains underscores (e.g.
`terminal_panel::Toggle`, `project_panel::ToggleFocus`), the keymap
editor showed **"No matches found for the provided query"**. Actions
without underscores (e.g. `zed::OpenLog`) worked fine.

I opened this issue for this
https://github.com/zed-industries/zed/issues/50223, but took the liberty
of sending a PR.

**Root cause:** `normalize_action_query` preserved underscores in the
query, but the search candidates are built with `humanize_action_name`
which converts underscores to spaces. The fuzzy matcher looked for `_`
in a candidate like `"terminal panel: toggle"` where it doesn't exist,
so matching always failed.

**Fix:** `normalize_action_query` now converts underscores to spaces
before the deduplication checks, consistent with `humanize_action_name`.
This also correctly collapses consecutive underscores with adjacent
spaces.

All three call sites of `normalize_action_query` (command palette
search, keymap editor filter, action completion provider) match against
humanized candidates, so the fix improves consistency across all of
them.

## Before (Left) / After (Right)
<img width="2560" height="1053" alt="Screenshot 2026-02-28 at 17 56 05"
src="https://github.com/user-attachments/assets/195530b6-57af-4270-9370-03744cb55e81"
/>
<img width="2557" height="1062" alt="Screenshot 2026-02-28 at 17 55 38"
src="https://github.com/user-attachments/assets/1e8637cd-86c9-496e-bc2b-f9f2d0ac23dc"
/>


Release Notes:

- Fixed keymap editor showing no results when opening "Change
Keybinding" from the command palette for actions with underscores in
their namespace (e.g. `terminal_panel::Toggle`,
`project_panel::ToggleFocus`)

crates/command_palette/src/command_palette.rs

@@ -43,24 +43,28 @@ pub struct CommandPalette {
     picker: Entity<Picker<CommandPaletteDelegate>>,
 }
 
-/// Removes subsequent whitespace characters and double colons from the query.
+/// Removes subsequent whitespace characters and double colons from the query, and converts
+/// underscores to spaces.
 ///
 /// This improves the likelihood of a match by either humanized name or keymap-style name.
+/// Underscores are converted to spaces because `humanize_action_name` converts them to spaces
+/// when building the search candidates (e.g. `terminal_panel::Toggle` -> `terminal panel: toggle`).
 pub fn normalize_action_query(input: &str) -> String {
     let mut result = String::with_capacity(input.len());
     let mut last_char = None;
 
     for char in input.trim().chars() {
-        match (last_char, char) {
+        let normalized_char = if char == '_' { ' ' } else { char };
+        match (last_char, normalized_char) {
             (Some(':'), ':') => continue,
-            (Some(last_char), char) if last_char.is_whitespace() && char.is_whitespace() => {
+            (Some(last_char), c) if last_char.is_whitespace() && c.is_whitespace() => {
                 continue;
             }
             _ => {
-                last_char = Some(char);
+                last_char = Some(normalized_char);
             }
         }
-        result.push(char);
+        result.push(normalized_char);
     }
 
     result
@@ -775,6 +779,14 @@ mod tests {
             normalize_action_query("editor: :GoToDefinition"),
             "editor: :GoToDefinition"
         );
+        assert_eq!(
+            normalize_action_query("terminal_panel::Toggle"),
+            "terminal panel:Toggle"
+        );
+        assert_eq!(
+            normalize_action_query("project_panel::ToggleFocus"),
+            "project panel:ToggleFocus"
+        );
     }
 
     #[gpui::test]