Round-seven fixes: swap name room for .tmp; input and notice details

- The shortened fallback swap name was capped at exactly NAME_MAX, so
  compaction's '<journal>.tmp' failed with ENAMETOOLONG on every
  checkpoint and the journal grew by a full copy of the buffer each
  time. Cap it at NAME_MAX - 4.
- A lone UTF-8 lead byte (8-bit Meta terminals) waited a second for
  continuation bytes on every key; wait 250 ms. An invalid byte now ends
  a pending ESC/C-k prefix instead of leaving it for the next key.
- Journal notices are shown after a deferred open's own status (which
  used to overwrite them), all pending ones at once, and the lock-out
  notice is not repeated after every save while the lock is still held.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015rcVQiiWyTzoNrsvLSaAfB

Swap.h

@@ -226,6 +226,7 @@ private:
 		// drop them until a checkpoint re-establishes the full content.
 		bool gap{false};
 		bool gap_notified{false}; // the user was told about the current gap
+		bool lockout_notified{false}; // told about the lock; kept across ResetJournal
 		std::uint64_t gap_chkpt_request_ns{0};
 		bool gap_unfixable_reported{false}; // gap on a buffer too large to checkpoint
 		// Another kte process holds this journal's lock: do not write to it.