feat: add lesson export and import functionality

- Implemented `LessonExport` and `LessonImport` actions in the action module.
- Added corresponding command parsing for lesson export and import.
- Created functions to handle lesson export and import in the memory module.
- Updated state management to reflect changes after lesson operations.
- Introduced deferred operations for handling asynchronous tasks in the event loop.
- Enhanced the tool execution context to include graduated checks for file operations.
- Added OAuth support with PKCE for secure authorization flows.
- Implemented a loopback server for handling OAuth redirects.
- Refactored various modules to improve code organization and maintainability.

src/controller/command.rs

@@ -0,0 +1,52 @@
+use crate::app::mode::ModeKind;
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum Command {
+    Help,
+    Quit,
+    Resume,
+    LessonCreate(String),
+    LessonExport(String),
+    LessonImport(String),
+    Mode(ModeKind),
+    Clear,
+    Save,
+    LessonList,
+    Unknown(String),
+}
+
+pub fn parse_command(text: &str) -> Command {
+    let text = text.trim();
+    if !text.starts_with('/') {
+        return Command::Unknown(text.to_string());
+    }
+    let parts: Vec<&str> = text.splitn(3, ' ').collect();
+    let cmd = parts[0];
+    let arg1 = parts.get(1).copied().unwrap_or("");
+    let arg2 = parts.get(2).copied().unwrap_or("");
+    match cmd {
+        "/help" => Command::Help,
+        "/quit" => Command::Quit,
+        "/resume" => Command::Resume,
+        "/clear" => Command::Clear,
+        "/save" => Command::Save,
+        "/mode" => {
+            let mode = match arg1 {
+                "chat" | "c" => ModeKind::Chat,
+                "agents" | "a" => ModeKind::Agents,
+                "bash" | "b" => ModeKind::Bash,
+                "workflow" | "w" => ModeKind::Workflow,
+                "help" | "h" => ModeKind::Help,
+                "settings" | "s" => ModeKind::Settings,
+                _ => return Command::Unknown(format!("unknown mode: {}", arg1)),
+            };
+            Command::Mode(mode)
+        }
+        "/lesson" if arg1 == "export" && !arg2.is_empty() => Command::LessonExport(arg2.to_string()),
+        "/lesson" if arg1 == "import" && !arg2.is_empty() => Command::LessonImport(arg2.to_string()),
+        "/lesson" if arg1 == "list" || arg1 == "ls" => Command::LessonList,
+        "/lesson" if !arg1.is_empty() => Command::LessonCreate(arg1.to_string()),
+        "/lesson" => Command::LessonList,
+        _ => Command::Unknown(cmd.to_string()),
+    }
+}