fix(tui): enable paste in MCP server configuration modal (#276)

Previously, when adding an MCP server (HTTP or stdio) or setting API keys,
users could not paste text into the input fields. This was because the
paste event (EngineEvent::Paste) was only routed to Form modals and the
main input widget, not to the unified modal stack that includes the MCP
manager modal.

Changes:
- Add handle_paste method to the Modal trait with default no-op impl
- Add handle_paste method to ModalStack to delegate to top modal
- Implement handle_paste in McpManagerModal for all text input modes:
  - AddStdioServer (name, command, args fields)
  - AddHttpServer (name, url fields)
  - SetAuth (api_key field)
  - SelectFromRegistry (search_query field)
- Update event loop to check modal_stack for paste events first

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt

cortex-tui/src/modal/mcp_manager.rs

@@ -1416,6 +1416,46 @@ impl Modal for McpManagerModal {
         "MCP Servers"
     }
 
+    fn handle_paste(&mut self, text: &str) -> bool {
+        match &mut self.mode {
+            McpMode::AddStdioServer {
+                name,
+                command,
+                args,
+                focus,
+            } => {
+                match focus {
+                    AddStdioServerFocus::Name => name.push_str(text),
+                    AddStdioServerFocus::Command => command.push_str(text),
+                    AddStdioServerFocus::Args => args.push_str(text),
+                }
+                true
+            }
+            McpMode::AddHttpServer { name, url, focus } => {
+                match focus {
+                    AddHttpServerFocus::Name => name.push_str(text),
+                    AddHttpServerFocus::Url => url.push_str(text),
+                }
+                true
+            }
+            McpMode::SetAuth {
+                server_name: _,
+                api_key,
+            } => {
+                api_key.push_str(text);
+                true
+            }
+            McpMode::SelectFromRegistry {
+                selected: _,
+                search_query,
+            } => {
+                search_query.push_str(text);
+                true
+            }
+            _ => false,
+        }
+    }
+
     fn desired_height(&self, max_height: u16, _width: u16) -> u16 {
         match &self.mode {
             McpMode::List => {

cortex-tui/src/modal/mod.rs

@@ -57,6 +57,12 @@ pub trait Modal: Send {
     /// Handle a key event, returning the result
     fn handle_key(&mut self, key: KeyEvent) -> ModalResult;
 
+    /// Handle pasted text. Returns true if the paste was handled.
+    /// Default implementation does nothing.
+    fn handle_paste(&mut self, _text: &str) -> bool {
+        false
+    }
+
     /// Key hints to display at the bottom
     fn key_hints(&self) -> Vec<(&'static str, &'static str)>;
 
@@ -243,6 +249,16 @@ impl ModalStack {
         }
     }
 
+    /// Handle pasted text, delegating to the top modal
+    /// Returns true if the paste was handled
+    pub fn handle_paste(&mut self, text: &str) -> bool {
+        if let Some(modal) = self.current_mut() {
+            modal.handle_paste(text)
+        } else {
+            false
+        }
+    }
+
     /// Clear all modals from the stack
     pub fn clear(&mut self) {
         self.stack.clear();

cortex-tui/src/runner/event_loop.rs

@@ -1672,10 +1672,13 @@ impl EventLoop {
             }
 
             EngineEvent::Paste(text) => {
-                // Check if a form modal is active and route paste to it
-                if let Some(crate::app::ActiveModal::Form(ref mut form_state)) =
+                // Check modal stack first (unified modal system)
+                if self.modal_stack.is_active() && self.modal_stack.handle_paste(&text) {
+                    // Paste was handled by modal
+                } else if let Some(crate::app::ActiveModal::Form(ref mut form_state)) =
                     self.app_state.active_modal
                 {
+                    // Check if a form modal is active and route paste to it
                     form_state.handle_paste(&text);
                 } else {
                     // Otherwise insert pasted text into the main input widget