fix(tmux): submit text as a bracketed paste so Codex does not swallow Enter

sendInput() typed the text of a text+Enter pair with `send-keys -l` and
sent Enter 50 ms later. Codex detects an unmarked paste from a fast
character burst and folds an Enter inside that window into the paste as a
newline, so the prompt stays in the composer unsubmitted. Measured with
codex-cli 0.162.1 in a throwaway tmux pane: 1505 chars stuck 3/3 as
`[Pasted Content 1506 chars]`, a 98-char line stuck 1/4. SubmitVerifier
re-presses Enter for the short case, but it cannot match the long one: the
composer shows the placeholder instead of the prompt's head.

The text now goes in via set-buffer + `paste-buffer -p -d` (markers only
when the pane requested bracketed paste), followed by the separate Enter as
before. Same pane, same texts: 4/4 and 3/3 submitted. Each send gets its
own named buffer; a paste that fails (pane or server gone) deletes it,
since tmux never trims named buffers on its own.

Also escapes a trailing `;` in the text, which tmux treats as a command
separator (`send-keys -l 'x;'` typed `x`, a lone `;` typed nothing).

sendInputToPane() has no callers in src/ and is left as it was.

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

docs/architecture-invariants.md

@@ -119,7 +119,7 @@ Spawn commands are pinned as literal strings in `test/cli-registry-spawn-golden.
 
 ### Input delivery and WS resilience
 
-**Input**: `session.writeViaMux()` for programmatic/curl input — tmux `send-keys -l` (literal) + `send-keys Enter`. Single-line only (fire-and-once). Interactive **browser** input goes through a durable **exactly-once** layer: each frame carries a stable `clientId` + monotonic per-session `seq`, persisted to localStorage until the server ACKs (`{t:'ia',seq}` over WS, or HTTP 2xx), so a dropped link/reconnect can't lose or double-deliver a prompt. A duplicate is ACKed as `{t:'ia',seq,dup:true,last}` so a client whose persisted counter rolled back below the server's watermark can lift itself out instead of typing into a silently dead terminal (`docs/reliable-input-delivery.md`). **WS resilience** (#149): the upgrade URL carries `cid = clientId + ':' + perTabNonce`, and `ws-connection-registry.ts` supersedes only same-TAB reconnects (two tabs on one session coexist; input frames keep the bare `clientId` for seq dedup); reconnects back off exponentially (attempts preserved across `_connectWs`), and the header connection chip renders from a real `_wsState` lifecycle (`connecting`/`connected`/`fallback`/`reconnecting`/`disconnected`).
+**Input**: `session.writeViaMux()` for programmatic/curl input — the text as one tmux bracketed paste (`paste-buffer -p`, so Codex cannot fold the Enter into a paste burst) + `send-keys Enter`. Single-line only (fire-and-once). Interactive **browser** input goes through a durable **exactly-once** layer: each frame carries a stable `clientId` + monotonic per-session `seq`, persisted to localStorage until the server ACKs (`{t:'ia',seq}` over WS, or HTTP 2xx), so a dropped link/reconnect can't lose or double-deliver a prompt. A duplicate is ACKed as `{t:'ia',seq,dup:true,last}` so a client whose persisted counter rolled back below the server's watermark can lift itself out instead of typing into a silently dead terminal (`docs/reliable-input-delivery.md`). **WS resilience** (#149): the upgrade URL carries `cid = clientId + ':' + perTabNonce`, and `ws-connection-registry.ts` supersedes only same-TAB reconnects (two tabs on one session coexist; input frames keep the bare `clientId` for seq dedup); reconnects back off exponentially (attempts preserved across `_connectWs`), and the header connection chip renders from a real `_wsState` lifecycle (`connecting`/`connected`/`fallback`/`reconnecting`/`disconnected`).
 
 ### Per-session env overrides: exact-key allowlist and CLAUDE_CONFIG_DIR