Implement double-escape session abort matching TUI behavior

- Add double-escape debounce pattern with 1-second timeout
- First escape shows warning, second escape aborts session
- Fix session busy check to handle undefined timeCompleted field
- Add abortSession API call to sessions store
- Show visual feedback in prompt input during debounce
- Remove Escape from filtered keys in prompt-input auto-focus

src/lib/shortcuts/escape.ts

@@ -1,8 +1,31 @@
 import { keyboardRegistry } from "../keyboard-registry"
 
+type EscapeKeyState = "idle" | "firstPress"
+
+const ESCAPE_DEBOUNCE_TIMEOUT = 1000
+
+let escapeKeyState: EscapeKeyState = "idle"
+let escapeTimeoutId: number | null = null
+let onEscapeStateChange: ((inDebounce: boolean) => void) | null = null
+
+export function setEscapeStateChangeHandler(handler: (inDebounce: boolean) => void) {
+  onEscapeStateChange = handler
+}
+
+function resetEscapeState() {
+  escapeKeyState = "idle"
+  if (escapeTimeoutId !== null) {
+    clearTimeout(escapeTimeoutId)
+    escapeTimeoutId = null
+  }
+  if (onEscapeStateChange) {
+    onEscapeStateChange(false)
+  }
+}
+
 export function registerEscapeShortcut(
   isSessionBusy: () => boolean,
-  interruptSession: () => void,
+  abortSession: () => Promise<void>,
   blurInput: () => void,
   closeModal: () => void,
 ) {
@@ -15,14 +38,27 @@ export function registerEscapeShortcut(
 
       if (hasOpenModal) {
         closeModal()
+        resetEscapeState()
         return
       }
 
       if (isSessionBusy()) {
-        interruptSession()
+        if (escapeKeyState === "idle") {
+          escapeKeyState = "firstPress"
+          if (onEscapeStateChange) {
+            onEscapeStateChange(true)
+          }
+          escapeTimeoutId = window.setTimeout(() => {
+            resetEscapeState()
+          }, ESCAPE_DEBOUNCE_TIMEOUT)
+        } else if (escapeKeyState === "firstPress") {
+          resetEscapeState()
+          abortSession()
+        }
         return
       }
 
+      resetEscapeState()
       blurInput()
     },
     description: "cancel/close",