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/edit.rs

@@ -0,0 +1,94 @@
+use std::fs;
+use std::path::PathBuf;
+use serde_json::{json, Value};
+use anyhow::{Result, anyhow};
+use super::super::Tool;
+use super::super::ToolCtx;
+use super::super::resolve_path;
+use super::helpers::arg_str;
+
+pub struct Edit;
+
+impl Tool for Edit {
+    fn name(&self) -> &'static str {
+        "edit"
+    }
+
+    fn description(&self) -> &'static str {
+        "Replace a string in a file with a new string. The old string must be unique unless replace_all is true."
+    }
+
+    fn parameters(&self) -> Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "path": {
+                    "type": "string",
+                    "description": "Path to the file to edit (relative to workspace root)"
+                },
+                "old": {
+                    "type": "string",
+                    "description": "The exact text to replace"
+                },
+                "new": {
+                    "type": "string",
+                    "description": "The replacement text"
+                },
+                "replace_all": {
+                    "type": "boolean",
+                    "description": "Replace all occurrences instead of requiring uniqueness"
+                },
+                "reason": {
+                    "type": "string",
+                    "description": "Reason for the change (must be non-empty)"
+                }
+            },
+            "required": ["path", "old", "new", "reason"]
+        })
+    }
+
+    fn run(&self, ctx: &ToolCtx, args: &Value) -> Result<String> {
+        let rel = arg_str(args, "path")?;
+        let old = arg_str(args, "old")?;
+        let new_str = arg_str(args, "new")?;
+        let reason = arg_str(args, "reason")?;
+        if reason.trim().is_empty() {
+            anyhow::bail!("reason must be a non-empty string");
+        }
+        let replace_all = args.get("replace_all").and_then(|v| v.as_bool()).unwrap_or(false);
+        let path: PathBuf = resolve_path(&ctx.workspaces, &rel)?;
+        if !path.exists() {
+            anyhow::bail!("file '{}' does not exist at resolved path {}", rel, path.display());
+        }
+        if path.is_dir() {
+            anyhow::bail!("'{}' is a directory, not a file", rel);
+        }
+        let content = fs::read_to_string(&path)
+            .map_err(|e| anyhow!("failed to read '{}': {}", rel, e))?;
+        if !content.contains(&old) {
+            anyhow::bail!("old string not found in '{}'", rel);
+        }
+        if !replace_all {
+            let count = content.matches(&old).count();
+            if count > 1 {
+                anyhow::bail!(
+                    "old string appears {} times in '{}'. Set replace_all=true to replace all occurrences, or provide a more specific match.",
+                    count, rel
+                );
+            }
+        }
+        let new_content = if replace_all {
+            content.replace(&old, &new_str)
+        } else {
+            content.replacen(&old, &new_str, 1)
+        };
+        fs::write(&path, &new_content)
+            .map_err(|e| anyhow!("failed to write '{}': {}", rel, e))?;
+        let bytes_diff = if new_content.len() > content.len() {
+            new_content.len() - content.len()
+        } else {
+            content.len() - new_content.len()
+        };
+        Ok(format!("edited {} ({} byte delta)", rel, bytes_diff as isize))
+    }
+}