chore(sensing-server): drop unused tracker_bridge imports

Iter 35 — every cargo check / cargo test since iter 15 has emitted the
same warning:

  warning: unused imports: `KeypointState`, `PoseTrack`, and `self`
   --> crates/wifi-densepose-sensing-server/src/tracker_bridge.rs:10

The three unused names date from before the bridge was refactored
to use the `pose_tracker::PoseTracker` direct import on line 12.
Removing them clears the noise without changing any behavior — the
file's actual uses (`TrackLifecycleState`, `TrackId`, `NUM_KEYPOINTS`)
stay imported via the narrowed `use { ... }` list.

After this commit `cargo check -p wifi-densepose-sensing-server` shows
only the pre-existing `rvf_container.rs:128 associated function 'new'
is never used` warning, which is unrelated to ADR-110 and out of scope
for this loop.

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

v2/crates/wifi-densepose-sensing-server/src/tracker_bridge.rs

@@ -7,7 +7,7 @@
 
 use std::time::Instant;
 use wifi_densepose_signal::ruvsense::{
-    self, KeypointState, PoseTrack, TrackLifecycleState, TrackId, NUM_KEYPOINTS,
+    TrackLifecycleState, TrackId, NUM_KEYPOINTS,
 };
 use wifi_densepose_signal::ruvsense::pose_tracker::PoseTracker;