Keep the session handoff notes out of the repository too

docs/handoff.md records where a working session stopped — unpushed commits,
what is mid-rewrite, which findings not to re-derive. That is scaffolding for
resuming work, not something a reader of the repository wants, and it points
at docs/launch.md, which is ignored for its own reasons.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: LarryLustig

.gitignore

@@ -33,6 +33,9 @@ playwright-report/
 # script in the repo you are about to post about is its own kind of own-goal.
 docs/launch.md
 
+# Session handoff notes. Working state for resuming, not repo content.
+docs/handoff.md
+
 # Editor directories
 .vscode/*
 !.vscode/extensions.json