agent: Use current shell (#28470)

Release Notes:

- agent: Replace `bash` tool with `terminal` tool which uses the current
shell

---------

Co-authored-by: Bennet <bennet@zed.dev>
Co-authored-by: Antonio <antonio@zed.dev>

crates/prompt_store/src/prompts.rs

@@ -14,12 +14,15 @@ use std::{
     time::Duration,
 };
 use text::LineEnding;
-use util::ResultExt;
+use util::{ResultExt, get_system_shell};
 
 #[derive(Serialize)]
 pub struct AssistantSystemPromptContext {
     pub worktrees: Vec<WorktreeInfoForSystemPrompt>,
     pub has_rules: bool,
+    pub os: String,
+    pub arch: String,
+    pub shell: String,
 }
 
 impl AssistantSystemPromptContext {
@@ -30,6 +33,9 @@ impl AssistantSystemPromptContext {
         Self {
             worktrees,
             has_rules,
+            os: std::env::consts::OS.to_string(),
+            arch: std::env::consts::ARCH.to_string(),
+            shell: get_system_shell(),
         }
     }
 }