fix(cron): send a paste-mode prompt's Enter as its own write

A cron job in "Paste (direct)" input mode wrote `<text>\r` into the pane
in one piece. Claude Code (measured on 2.1.283) takes a burst of about a
hundred characters as a paste, so the `\r` landed as a newline and the
prompt sat unsent on the composer while the run reported `prompt_sent`.

Delivery now lives in `deliverCronPrompt()`. Paste mode writes the text
raw, waits CRON_PASTE_ENTER_DELAY_MS (300 ms), sends `\r` as a separate
write down the same PTY (so it cannot overtake the text), and arms the
session's composer check through the new public
`Session.verifySubmitted()`, which re-presses Enter while the prompt is
still visibly unsent. A session with nothing to write to now fails the
run instead of reporting the prompt as sent. Typed mode is unchanged.

Verified on an isolated instance: a paste-mode job with a 104-character
prompt submitted on the first Enter and Claude answered.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/config/server-timing.ts

@@ -99,3 +99,11 @@ export const STALE_DATA_MAX_AGE_MS = 60 * 60 * 1000;
 
 /** Standard 5-minute inactivity timeout for streams and caches (ms) */
 export const INACTIVITY_TIMEOUT_MS = 5 * 60 * 1000;
+
+/**
+ * Gap between a paste-mode cron prompt's text and its Enter (ms). The two must be
+ * separate writes: Claude Code takes a raw `<text>\r` burst of about a hundred
+ * characters as a paste and turns its `\r` into a newline. A separate `\r` 80 ms
+ * after the text was measured to submit; this leaves room for a longer prompt.
+ */
+export const CRON_PASTE_ENTER_DELAY_MS = 300;