feat: Implement lightweight UDP interactive UI for Neovim

- Rewrote gemini-ui.lua to send native Neovim prompt selections, Ghost Text diff accept/reject actions, and smart context highlighting directly to the backend via zero-latency UDP port 3002, entirely replacing the old xecute_agent terminal subprocesses.
- Added prompt_user and preview_diff extmark lua functions for non-destructive diff review.
- Updated the Rust backend mcp-memory-server UDP listener to ingest the new gent_ask and interactive schema payloads and route them to the EventBus.
- Updated README.md and instructions.md with UDP documentation.

server/src/api/telemetry.rs

@@ -9,6 +9,14 @@ pub struct NvimTelemetry {
     pub file: Option<String>,
     pub line: Option<i64>,
     pub col: Option<i64>,
+    // New interactive fields
+    pub prompt: Option<String>,
+    pub response: Option<String>,
+    pub index: Option<i64>,
+    pub request_id: Option<String>,
+    pub diff_id: Option<String>,
+    pub start_row: Option<i64>,
+    pub end_row: Option<i64>,
 }
 
 pub async fn nvim_telemetry_handler(