Add one-click BUZZ Story Bridge live proof

[BryanHarrisScripts]

Summary

Expose the real #1422 live proof in the exact Foundations Story Workflow panel used by the Windows product journey.

This adds a Run BUZZ Story Test action that:

• uses one queued Foundations Story Work Item and the existing Tamsin Responsibility Run/context packet;
• requires the locally bound official Tamsin BUZZ public signer;
• creates/resolves the private project Story Room;
• ensures Tamsin is a bot member of that private room before dispatch;
• targets Tamsin with BUZZ v0.5.19's explicit --mention <pubkey> support;
• gives the managed Agent a strict Story Bridge result-envelope contract;
• proves retry dispatch is idempotent;
• waits for a real Tamsin-signed contribution and requires signature verification;
• re-collects under a simulated revision advance and requires the same contribution to be stale/rejected;
• snapshots the active PPF before/after and fails if BUZZ transport mutates it;
• records only a Responsibility Run proposal artifact, never a PPF/canon write.

The existing Run story checks local path remains unchanged and separate.

BUZZ v0.5.19 explicitly requires private-channel membership for ACP Agent discovery and supports explicit message mentions, so the transport adds only those bounded primitives to the existing localhost BUZZ gateway.

Relates to #1422. Do not close #1422 until the user runs this on the real Afterglow working copy and receives PASS.