Warn on unmatched CLI paths; send Kafka failure/SMTP TLS reports per-report (#890)

Fixes the two remaining bugs and the nits uncovered during the review
session:

- The CLI logs a warning for each file_path argument that matches no
  files, instead of silently succeeding with empty results — a typo'd
  path in a cron job previously 'worked' forever while processing
  nothing (_expand_file_path_args dropped it as a zero-match glob).
  Deliberately a warning, not an error: a glob legitimately matching
  nothing must not break existing workflows, and mailbox-only runs
  stay silent.

- save_failure_reports_to_kafka and save_smtp_tls_reports_to_kafka now
  send one message per report, mirroring the aggregate saver's
  per-slice sends. Every released version documented per-record sends,
  but the code sent the whole list as one message, which a large batch
  — failure reports carry message samples — could push past Kafka's
  default 1MB message limit. Consumer-visible: these topics now carry
  individual report objects, not one JSON array per batch.

- The CLI module docstring and argparse description now mention SMTP
  TLS reports; usage.md's CLI-help mirror regenerated.

- The elastic/opensearch to_header display-name tests now assert the
  joined 'RT <rcpt@example.com>' string reaches the saved document
  (autospec save), plus the exactly-once call, instead of only that
  save ran.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

docs/source/usage.md

@@ -11,7 +11,7 @@ usage: parsedmarc [-h] [-c CONFIG_FILE] [-r] [--strip-attachment-payloads] [-o O
                   [-w] [--verbose] [--debug] [--log-file LOG_FILE] [--no-prettify-json] [-v]
                   [file_path ...]
 
-Parses DMARC reports
+Parses DMARC and SMTP TLS reports
 
 positional arguments:
   file_path             one or more paths to aggregate, failure, or SMTP TLS report files, emails, mbox files, or