docs(planning): mark Phase 1.5 live broadcast as Done

Tasks 1.5.4, 1.5.5, 1.5.6 marked 🟩 with commit hashes and implementation
notes. Phase 1.5 status updated to Done in ROADMAP.md.

.planning/phase-1-5-live-broadcast/04-broadcast-consumer-group.md

@@ -1,7 +1,7 @@
 # Task 1.5.4 — Broadcast consumer group & fan-out
 
 **Phase:** 1.5 — Live broadcast
-**Status:** ⬜ Not started
+**Status:** 🟩 Done
 **Depends on:** 1.5.3
 **Wiki refs:** `docs/wiki/synthesis/processor-ws-contract.md` §Streaming updates, §Multi-instance behaviour; `docs/wiki/concepts/live-channel-architecture.md` §Multi-instance Processor
 
@@ -218,4 +218,8 @@ Per the contract: omit fields rather than send `null` for absent values.
 
 ## Done
 
-(Filled in when the task lands.)
+Landed in `c07ea0e`. Key implementation decisions:
+
+- `CodecError`/`decodePosition` moved to `src/shared/codec.ts`; `Position`/`AttributeValue` moved to `src/shared/types.ts`. Both `src/core/` and `src/live/` re-export from shared to preserve existing import paths.
+- `broadcast.ts` ACKs all stream entries immediately (durability not needed for fan-out).
+- Test uses a `stopSignal` Promise to coordinate between the broadcast loop and the test's `stop()` call, avoiding the tight-loop OOM that naive polling triggers.