fix(branch-coord): revert ADR-115 Cargo.toml/cli.rs that slipped into iter 18

Iter 18's commit 2997165bc accidentally absorbed the ADR-115 agent's
uncommitted MQTT/Matter additions (Cargo.toml `rumqttc` dep + [features]
block, cli.rs --mqtt CLI flags) into the adr-110-esp32c6 branch during
the cross-branch checkout described in that commit's message.

The actual iter 18 EMA work in main.rs is correct and stays; this commit
restores Cargo.toml + cli.rs to their HEAD~1 (iter 17) state so the
ADR-115 agent's stashed `stash@adr115-pending-work` can be popped cleanly
back onto their feat/adr-115-ha-mqtt-matter branch without colliding.

Net effect on adr-110-esp32c6:
  - main.rs iter 18 EMA: kept ✓
  - 4 fps_ema_tests: still green
  - Cargo.toml: back to iter-17 state (wifi-densepose-hardware dep only)
  - cli.rs: back to iter-17 state (no MQTT flags)
  - Cargo.lock: synced to match

The ADR-115 agent can pop their stash on feat/adr-115-ha-mqtt-matter
and resume without merging an unrelated branch's ADR-110 work.

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/Cargo.lock

@@ -9189,6 +9189,7 @@ dependencies = [
  "tracing",
  "tracing-subscriber",
  "ureq 2.12.1",
+ "wifi-densepose-hardware",
  "wifi-densepose-signal",
  "wifi-densepose-wifiscan",
 ]