docs: finish dropping the stripped-newline rule from the input docs

The first commit left the old rule standing in places: the gotchas list in
extending-codeman.md still said newlines were stripped and that
"echo A\necho B\r" ran `echo Aecho B`, and so did both READMEs and the
skill's big-input section. Those now describe the paste.

Newlines are only kept on the mux path, so the docs that describe the paste
say "with useMux": without it a multi-line body is not a plain prompt and is
written straight into the pane.

Cron keeps rejecting multi-line prompts, but its docs and the code comments
in cron-service.ts, schemas.ts and respawn-controller.ts gave a reason this
change removes (writeViaMux joining lines, a newline submitting in Ink). The
reason that remains is the submit check, which cannot recognise a
multi-line paste in the composer, and for cron's paste mode the newlines
reaching the CLI as keys.

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

docs/wiki/Cron-Jobs.md

@@ -51,10 +51,11 @@ or a server restart shifts later runs slightly. That drift is accepted rather th
 
 ## Prompts are single line
 
-This is the rule people trip over. Programmatic input into an agent session is single line
-everywhere in Codeman, because the terminal UIs these CLIs use treat a newline as submit. A
-multi-line prompt would be silently mangled, so it is **rejected** instead: the form refuses
-it, and a prompt file whose contents are multi-line fails the run with a clear message.
+This is the rule people trip over. A cron job fires with nobody watching, and the check that
+re-presses an Enter the agent ignored cannot recognise a multi-line paste in the composer, so
+a multi-line prompt could sit there unsent. In `paste` mode the newlines would reach the agent
+as keys. So a multi-line prompt is **rejected**: the form refuses it, and a prompt file whose
+contents are multi-line fails the run with a clear message.
 
 For anything longer than a sentence, put the instructions in a file and make the prompt tell
 the agent to read it:

docs/wiki/Driving-Codeman-From-An-Agent.md

@@ -127,11 +127,12 @@ Read these before writing any code. Each one has cost somebody an afternoon.
 
 1. **Input must end with `\r`.** Enter fires only when the payload contains a carriage
    return. Without it the text sits unsubmitted on the prompt, the request still succeeds,
-   and a combined wait burns its full timeout on a turn that never started. Embedded
-   newlines are kept: the text goes in as one paste and the Enter after it submits all of
-   it, so `"echo A\necho B\r"` runs both commands in a shell. The check that re-presses a
-   stranded Enter cannot reliably recognise a multi-line paste, so a long multi-line
-   prompt to a just-started agent is still safer in a file it is told to read.
+   and a combined wait burns its full timeout on a turn that never started. With
+   `useMux`, embedded newlines are kept: the text goes in as one paste and the Enter after
+   it submits all of it, so `"echo A\necho B\r"` runs both commands in a shell. The check
+   that re-presses a stranded Enter cannot reliably recognise a multi-line paste, so a
+   long multi-line prompt to a just-started agent is still safer in a file it is told to
+   read.
 2. **Make input idempotent.** Send a stable `clientId` and a monotonic per-session `seq`. The
    server deduplicates, so a retry after a dropped connection cannot double-deliver.
 3. **Auth.** With `CODEMAN_PASSWORD` set, use HTTP Basic or the session cookie. A missing

docs/wiki/Input-And-Voice.md

@@ -125,9 +125,9 @@ Sending prompts over the API has one rule that catches everyone: **the payload m
 `\r`** or Enter is never sent. The request still succeeds, the text sits unsubmitted in the
 composer, and any wait burns its whole timeout on a turn that never started.
 
-Embedded newlines are kept: multi-line input goes in as one paste and the Enter after it
-submits all of it, so `"echo A\necho B\r"` runs both commands in a shell. The check that
-re-presses a stranded Enter cannot reliably recognise a multi-line paste, so long
+With `useMux`, embedded newlines are kept: multi-line input goes in as one paste and the
+Enter after it submits all of it, so `"echo A\necho B\r"` runs both commands in a shell. The
+check that re-presses a stranded Enter cannot reliably recognise a multi-line paste, so long
 multi-line content is still safer in a file the agent is told to read.
 
 See [Driving Codeman From An Agent](Driving-Codeman-From-An-Agent).