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/settings/src/settings_content/terminal.rs

@@ -348,6 +348,22 @@ pub struct TerminalToolbarContent {
     pub breadcrumbs: Option<bool>,
 }
 
+#[derive(
+    Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize, JsonSchema, MergeFrom,
+)]
+#[serde(rename_all = "snake_case")]
+pub enum CondaManager {
+    /// Automatically detect the conda manager
+    #[default]
+    Auto,
+    /// Use conda
+    Conda,
+    /// Use mamba
+    Mamba,
+    /// Use micromamba
+    Micromamba,
+}
+
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, JsonSchema, MergeFrom)]
 #[serde(rename_all = "snake_case")]
 pub enum VenvSettings {
@@ -360,6 +376,10 @@ pub enum VenvSettings {
         activate_script: Option<ActivateScript>,
         venv_name: Option<String>,
         directories: Option<Vec<PathBuf>>,
+        /// Preferred Conda manager to use when activating Conda environments.
+        ///
+        /// Default: auto
+        conda_manager: Option<CondaManager>,
     },
 }
 #[skip_serializing_none]
@@ -367,6 +387,7 @@ pub struct VenvSettingsContent<'a> {
     pub activate_script: ActivateScript,
     pub venv_name: &'a str,
     pub directories: &'a [PathBuf],
+    pub conda_manager: CondaManager,
 }
 
 impl VenvSettings {
@@ -377,10 +398,12 @@ impl VenvSettings {
                 activate_script,
                 venv_name,
                 directories,
+                conda_manager,
             } => Some(VenvSettingsContent {
                 activate_script: activate_script.unwrap_or(ActivateScript::Default),
                 venv_name: venv_name.as_deref().unwrap_or(""),
                 directories: directories.as_deref().unwrap_or(&[]),
+                conda_manager: conda_manager.unwrap_or(CondaManager::Auto),
             }),
         }
     }