Commits of agents carry a co-author trailer naming the model

A git wrapper (docker/git-coauthor -> /usr/local/lib/codecraft/bin/git) adds
--trailer "$CODECRAFT_COMMIT_TRAILER" right after the commit subcommand; the
agent shell puts it first on PATH and sets the trailer in the script itself
(works inside the sandbox, which clears the environment). Default text:
"Co-Authored-By: {model} ({provider}) via CodeCraft" (server.commit_trailer,
Settings -> General; empty = off). Git skips duplicates (amend, model wrote it).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/i18n/en.ts

@@ -769,6 +769,9 @@ export const en = {
   "settings.smallModelHint": "Used for session titles. Compaction uses the session model.",
   "settings.currency": "Currency",
   "settings.autoCompact": "Auto-compact at",
+  "settings.commitTrailer": "Commit note of agents",
+  "settings.commitTrailerOff": "off",
+  "settings.commitTrailerHint": "Added as a trailer to every git commit an agent makes. {model} = model name, {provider} = provider, {model_id} = model id. Empty = off. Your own commits stay unchanged.",
   "settings.autoCompactHint": "Fraction of the context window (0 = off).",
   "settings.craft": "Craft mode",
   "settings.cleanRoom": "Clean room",