fix(windows): make Ctrl-C interrupt panes and multi-line paste arrive as one block

[whackur]

Two Windows-only defects in terminal panes. Both were reproduced, root-caused against real evidence, and verified running.

Ctrl-C never interrupted a running program

ping 8.8.8.8 in a pane could not be stopped. The input path was already correct — map_key leaves Ctrl-C unmapped, encode_key emits 0x03, send_input writes and flushes.

The cause is a console disposition: a process inherits its parent's ignore-Ctrl-C flag, and daemon::detach passes CREATE_NEW_PROCESS_GROUP, which sets that flag outright. Every ConPTY pane inherited it. conhost still delivered the 0x03 byte — an idle prompt abandoned its line, so it looked wired up — but raised no CTRL_C_EVENT.

Verified with a portable-pty probe: with the flag set, ping survives 0x03; after SetConsoleCtrlHandler(NULL, FALSE), the same byte produces ^C and kills it.

The clear lands in run_daemon, not the TUI: attach owns no hub and only forwards keystrokes over the socket, so the daemon is the ConPTY parent.

Multi-line paste split into one submission per line

crossterm's Windows event source produces only Key/Mouse/WindowBufferSize/Focus records — Event::Paste never fires, so EnableBracketedPaste is a no-op there and a paste arrives as one key press per character.

input::burst coalesces the burst into a synthetic Event::Paste, reusing the existing bracketed-paste path unchanged. Two details came out of instrumented runs rather than reasoning:

• Enter must become \r, not \n. Terminals normalise paste line breaks to CR; \n is dropped by some readers, collapsing the lines.
• The drain cannot use a zero-wait poll. The console feeds a paste in incrementally, so the queue reads momentarily empty and the paste is cut mid-word into many separate bracketed blocks. A 5 ms gap bridges it, far below human typing cadence.

The classifier is deliberately narrow — every event a plain unmodified character or Enter press, and either Enter plus another character or more than 16 characters — because a false positive submits typed keys as a block. Anything else falls back to per-event dispatch in arrival order.

Verification

cargo fmt --all --check, cargo build, cargo clippy --all-targets --all-features -- -D warnings, cargo test (1457 passed). 10 new tests cover the classification rule.

Confirmed by hand in a real pane: ping stops on Ctrl-C, and a 7-line paste arrives as a single block with no loss. Unix behaviour is untouched — the Unix seam is a no-op and the burst call site is #[cfg(windows)].