Implement chat and markdown views, enhance status bar, and add workflow panel

- Added `chat.rs` for rendering chat messages with timestamps and roles.
- Introduced `markdown.rs` for rendering markdown content with styling.
- Created `status.rs` to display the application status bar with session and message counts.
- Developed `workflow.rs` to show the current workflow status, including tool calls and active jobs.
- Established a `theme.rs` for centralized color management across the UI.
- Updated `mod.rs` to include new modules and manage rendering logic.

src/tool/fs/helpers.rs

@@ -0,0 +1,27 @@
+use std::path::Path;
+use serde_json::Value;
+use anyhow::{Result, anyhow};
+
+pub fn arg_str(args: &Value, name: &str) -> Result<String> {
+    args.get(name)
+        .and_then(|v| v.as_str())
+        .map(|s| s.to_string())
+        .ok_or_else(|| anyhow!("missing required argument: {}", name))
+}
+
+pub fn not_found_help(ctx: &super::super::ToolCtx, path: &Path, rel: &str) -> String {
+    let canon = path.canonicalize().unwrap_or_else(|_| path.to_path_buf());
+    let in_ws = ctx.workspaces.iter().any(|w| {
+        let wc = w.canonicalize().unwrap_or_else(|_| w.to_path_buf());
+        canon.starts_with(&wc)
+    });
+    if !in_ws {
+        format!(
+            "path '{}' is outside all workspace roots. Workspace roots: {}",
+            rel,
+            ctx.workspaces.iter().map(|w| w.display().to_string()).collect::<Vec<_>>().join(", ")
+        )
+    } else {
+        format!("path '{}' does not exist (resolved to {})", rel, canon.display())
+    }
+}