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/research/rf-topological-sensing/10-system-architecture-prototype.md

@@ -337,7 +337,7 @@ Usage in rf_topology:
 ### 3.1 Module Location
 
 ```
-rust-port/wifi-densepose-rs/crates/wifi-densepose-signal/src/ruvsense/
+v2/crates/wifi-densepose-signal/src/ruvsense/
   rf_topology.rs          <-- New module (primary)
   rf_topology/
     graph.rs              <-- RfGraph aggregate root
@@ -351,7 +351,7 @@ rust-port/wifi-densepose-rs/crates/wifi-densepose-signal/src/ruvsense/
 Alternatively, rf_topology could be a standalone crate:
 
 ```
-rust-port/wifi-densepose-rs/crates/wifi-densepose-topology/
+v2/crates/wifi-densepose-topology/
   src/
     lib.rs
     graph.rs