feat(core): verify output integrity before replacing original

After ffmpeg exits successfully, run ffprobe against the temporary
output file to confirm it is a valid, playable media file before
replacing the original. If the probe fails the temporary file is removed
and the encode is treated as a runtime failure, leaving the original
untouched.

This guards against cases where ffmpeg exits 0 but has written a
truncated or corrupt container (e.g. due to a disk-full condition
mid-write, a codec bug, or a preset producing an unreadable stream).

The check is enabled by default and can be disabled via
--no-verify-output or [encoding] verify_output = false in config.toml
for large batch jobs on trusted encoders where the extra ffprobe
  round-trip is undesirable.

The --continue flag is honoured: a failed integrity check counts as a
runtime failure for the purposes of deciding whether to proceed to the
next file.

Docs, man page, bash completion, and README updated accordingly.

1 files changed, 2 insertions, 0 deletions

diff --git a/transcode.sh.bash-completion b/transcode.sh.bash-completion
index 558cf09..9fc4701 100644
--- a/transcode.sh.bash-completion
+++ b/transcode.sh.bash-completion
@@ -120,6 +120,8 @@ _transcode_sh() {
             local longopts='
                 --continue
                 --no-continue
+                --verify-output
+                --no-verify-output
                 --config-file
                 --config-file=
                 --encode-file