terminal: Allow configuring conda manager (#40577)

Closes #40576
This PR makes Conda activation configurable and transparent by adding a
`terminal.detect_venv.on.conda_manager` setting (`"auto" | "conda" |
"mamba" | "micromamba"`, default `"auto"`), updating Python environment
activation to honor this preference (or the detected manager executable)
and fall back to `conda` when necessary.

The preference is passed via `ZED_CONDA_MANAGER` from the terminal
settings, and the activation command is built accordingly (with proper
quoting for paths). Changes span
`zed/crates/terminal/src/terminal_settings.rs` (new `CondaManager` and
setting), `zed/crates/project/src/terminals.rs` (inject env var),
`zed/crates/languages/src/python.rs` (activation logic), and
`zed/assets/settings/default.json` (document the setting). Default
behavior remains unchanged for most users while enabling explicit
selection of `mamba` or `micromamba`.

Release Notes:
- Added: terminal.detect_venv.on.conda_manager setting to choose the
Conda manager (auto, conda, mamba, micromamba). Default: auto.
- Changed: Python Conda environment activation now respects the
configured manager, otherwise uses the detected environment manager
executable, and falls back to conda.
- Reliability: Activation commands quote manager paths to handle spaces
across platforms.
- Compatibility: No breaking changes; non-Conda environments are
unaffected; remote terminals are supported.

---------

Co-authored-by: Lukas Wirth <me@lukaswirth.dev>
Co-authored-by: Lukas Wirth <lukas@zed.dev>

crates/project/src/project_tests.rs

@@ -10185,7 +10185,7 @@ fn python_lang(fs: Arc<FakeFs>) -> Arc<Language> {
                 manifest_name: ManifestName::from(SharedString::new_static("pyproject.toml")),
             }
         }
-        fn activation_script(&self, _: &Toolchain, _: ShellKind) -> Vec<String> {
+        fn activation_script(&self, _: &Toolchain, _: ShellKind, _: &gpui::App) -> Vec<String> {
             vec![]
         }
     }

crates/project/src/terminals.rs

@@ -127,8 +127,10 @@ impl Project {
                         .language_for_name(&toolchain.language_name.0)
                         .await
                         .ok();
-                    let lister = language?.toolchain_lister();
-                    return Some(lister?.activation_script(&toolchain, shell_kind));
+                    let lister = language?.toolchain_lister()?;
+                    return cx
+                        .update(|cx| lister.activation_script(&toolchain, shell_kind, cx))
+                        .ok();
                 }
                 None
             })
@@ -317,7 +319,8 @@ impl Project {
                 .unwrap_or_else(get_default_system_shell),
             None => settings.shell.program(),
         };
-        let shell_kind = ShellKind::new(&shell, self.path_style(cx).is_windows());
+
+        let is_windows = self.path_style(cx).is_windows();
 
         // Prepare a task for resolving the environment
         let env_task =
@@ -325,6 +328,7 @@ impl Project {
 
         let lang_registry = self.languages.clone();
         cx.spawn(async move |project, cx| {
+            let shell_kind = ShellKind::new(&shell, is_windows);
             let mut env = env_task.await.unwrap_or_default();
             env.extend(settings.env);
 
@@ -337,13 +341,16 @@ impl Project {
                         .language_for_name(&toolchain.language_name.0)
                         .await
                         .ok();
-                    let lister = language?.toolchain_lister();
-                    return Some(lister?.activation_script(&toolchain, shell_kind));
+                    let lister = language?.toolchain_lister()?;
+                    return cx
+                        .update(|cx| lister.activation_script(&toolchain, shell_kind, cx))
+                        .ok();
                 }
                 None
             })
             .await
             .unwrap_or_default();
+
             let builder = project
                 .update(cx, move |_, cx| {
                     let (shell, env) = {