fix(release): restore the generated agent docs when prepare-release fails

prepare-release.sh snapshots every file it may rewrite and restores them
if any later gate fails, but web/data/agent-docs.generated.json was not
on that list. derive-facts.mjs regenerates it from docs/INSTALL.md, so a
failed `prepare-release.sh 0.10.3` (for example, before the changelog
section exists) left that tracked file holding the bumped INSTALL.md
content in the shared checkout. Found in a 0.10.3 bump dry run on a
copy of 9f6999f99d.

Verified: scripts/release/prepare-release.test.sh exits 0 on an export
of origin/main with this change.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

scripts/release/prepare-release.sh

@@ -56,6 +56,7 @@ transaction_paths=(
   "${readmes[@]}"
   crates/tui/CHANGELOG.md
   web/lib/facts.generated.ts
+  web/data/agent-docs.generated.json
   crates/config/src/route/providers-export.golden.json
   crates/tui/src/commands/contract/fixtures/config_policy/status.json
 )