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/ddd/sensing-server-domain-model.md

@@ -14,7 +14,7 @@ This document defines the system using [Domain-Driven Design](https://martinfowl
 | 4 | [Training Pipeline](#4-training-pipeline-context) | Background training runs, progress streaming, contrastive pretraining | [ADR-043](../adr/ADR-043-sensing-server-ui-api-completion.md) | `sensing-server/src/training_api.rs` |
 | 5 | [Visualization](#5-visualization-context) | WebSocket streaming to web UI, Gaussian splat rendering, data transparency | [ADR-019](../adr/ADR-019-sensing-only-ui-mode.md), [ADR-035](../adr/ADR-035-live-sensing-ui-accuracy.md) | `ui/` |
 
-All code paths shown are relative to `rust-port/wifi-densepose-rs/crates/wifi-densepose-` unless otherwise noted.
+All code paths shown are relative to `v2/crates/wifi-densepose-` unless otherwise noted.
 
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