feat(call-to-play)!: coordinate game sessions across peers

Implement the launcher design as a production peer-to-peer feature. Call to
Play actions are immutable, validated events broadcast over the existing QUIC
control channel, deduplicated in a bounded in-memory history, and exchanged in
Hello/HelloAck so late joiners reconstruct current calls.

Add the Tauri bridge and modular launcher surfaces for play-now and scheduled
calls, check-in, readiness buffers, role-aware controls, chat, tickers, and
actual caller launch. A deterministic frontend reducer derives presentation
state from replicated history. Extend the JSONL peer harness with publish/list
commands and a three-peer live-delivery and late-join scenario.

This intentionally raises the only supported wire protocol from version 5 to
version 6; older builds are not supported. Document the transport architecture
and exclude generated peer-test state from Docker build contexts.

Test Plan:
- `just fmt` -- passed
- `just clippy` -- passed
- `just test` -- passed
- `just frontend-test` -- passed, 20 tests
- `just build` -- passed
- `just peer-cli-tests S2 S48` -- passed
- `git diff --cached --check` -- passed

PEER_CLI_SCENARIOS.md

@@ -55,6 +55,7 @@ for deterministic local runs; mDNS/macvlan remains an environment smoke path.
 | S45 | Sender disconnect during streamed install | A source serves large catalog-version `alienswarm`; after the client receives the first streamed chunk, the source container is killed. | The operation reaches a terminal failure/peers-gone event, emits no download/install success, clears active operations, and rolls back local/staging state. |
 | S46 | Receiver cancel during streamed install | A client starts streaming large catalog-version `alienswarm`, receives the first chunk, then sends `cancel-download alienswarm`. | The receiver cancels without emitting download/install success or a user-visible download failure, clears active operations, and rolls back local/staging state. |
 | S47 | Multi-archive streamed install order | A source serves `fixture-multi/cnctw` with two root `.eti` archives named to require sorted processing. | Streamed chunk paths arrive in root archive sort order, both payloads install under `local/`, the receiver is local-only installed, and no root archives or sentinel are committed. |
+| S48 | Call to Play replication and late join | Alice and Bob connect; Alice publishes a call, then Bob publishes an RSVP and chat message. Charlie joins afterward and handshakes with Alice. | Alice and Bob receive the live events, while Charlie reconstructs the same three-event history during handshake with no duplicate event IDs. |
 
 ## Version-Skew Contract
 
@@ -143,6 +144,14 @@ Use S39-S41 to pin down low-disk streamed installs:
 
 ## Run Log
 
+### 2026-07-21 - Call to Play Transport (S48)
+
+- Added JSONL commands to publish and inspect Call to Play events.
+- S2 passed against the rebuilt image, preserving bidirectional library
+  exchange after the protocol version bump.
+- S48 passed against the rebuilt image: create, RSVP, and chat propagated live,
+  then a late third peer received the same deduplicated history in handshake.
+
 ### 2026-06-21 - Test-Suite Integrity Audit And Hardening
 
 - An adversarial review of `run_extended_scenarios.py` found assertions that