chore(repo): rename rust-port/wifi-densepose-rs → v2/ (flatten to one level) (#427)

The Rust port lived two directories deep (rust-port/wifi-densepose-rs/)
without any sibling under rust-port/ that warranted the extra level.
Move the whole workspace up to v2/ to match v1/ (Python) at the same
depth and shorten every cd / build command across the repo.

git mv preserves history for all tracked files. 60 files updated for
path references (CI workflows, ADRs, docs, scripts, READMEs, internal
.claude-flow state). Two manual fixes for relative-cd paths in
CLAUDE.md and ADR-043 that became wrong after the depth change
(cd ../.. → cd ..).

Validated:
- cargo check --workspace --no-default-features → clean (after target/
  nuke; the gitignored target/ was carried by the OS rename and had
  hard-coded old paths in build scripts)
- cargo test --workspace --no-default-features → 1,539 passed, 0 failed,
  8 ignored (same totals as pre-rename)
- ESP32-S3 on COM7 → still streaming live CSI (cb #40300, RSSI -64 dBm)

After-merge follow-up: contributors should `rm -rf v2/target` once and
let cargo regenerate from the new path.

docs/WITNESS-LOG-028.md

@@ -35,7 +35,7 @@ git checkout 96b01008
 ### Step 2: Rust Workspace — Full Test Suite
 
 ```bash
-cd rust-port/wifi-densepose-rs
+cd v2
 cargo test --workspace --no-default-features
 ```
 
@@ -89,7 +89,7 @@ ls firmware/esp32-csi-node/build/*.bin 2>/dev/null || echo "App binary in build/
 ### Step 6: Verify ADR-018 Binary Frame Parser
 
 ```bash
-cd rust-port/wifi-densepose-rs
+cd v2
 cargo test -p wifi-densepose-hardware --no-default-features
 ```