R-304 option C: operator mail when a household's code opens or may open an older package (once a day); R-298 side fix (no eject/format on a backup-target drive); R-717 comments

Unreleased; ships with tomorrow's release (needs the hub of the same day).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/stacks/signup_block.go

@@ -19,7 +19,7 @@ import (
 // without a gate. The household lets a family member join by opening sign-up for 15 minutes from the app page
 // (OpenSignupWindow); the loop closes it again. Decided by CC unattended 2026-09-29 — the operator may reverse.
 //
-//   signup_block: "PathPrefix(`/-/register`)"     # opengist
+//   signup_block: "PathRegexp(`(?i)^/+-/+register`)"     # opengist (catalog templates/opengist/.felhom.yml)
 //
 // Only an app whose setup gate this box opened carries a block: an app installed before (no gate record) is never
 // touched — the same rule as the gate itself (Part 0, 2026-09-29).