chore(repo): move v1/ → archive/v1/ + add archive/README.md (#430)

The Rust port at v2/ has been the primary codebase since the rename
in #427. The Python implementation at v1/ is no longer the active
target; the only load-bearing path is the deterministic proof bundle
at v1/data/proof/ (per ADR-011 / ADR-028 witness verification).

Move the whole Python tree into archive/v1/ and document the policy
in archive/README.md: no new features, bug fixes only when they affect
a still-load-bearing path (currently just the proof), CI continues to
verify the proof on every push and PR.

Path references updated in 26 files via path-pattern sed (only
matches v1/<known-child> patterns, never bare v1 or API URLs like
/api/v1/). Two double-prefix typos (archive/archive/v1/) caught and
hand-fixed in verify-pipeline.yml and ADR-011.

Validated:
- Python proof verify.py imports cleanly at archive/v1/data/proof/
  (numpy/scipy still required; CI installs requirements-lock.txt
  from archive/v1/ now)
- cargo test --workspace --no-default-features → 1,539 passed,
  0 failed, 8 ignored (unaffected by Python tree relocation)
- ESP32-S3 on COM7 untouched (no firmware paths changed)

After-merge: contributors should re-run any local `python v1/...`
commands as `python archive/v1/...` (CLAUDE.md and CHANGELOG already
updated).

README.md

@@ -92,7 +92,7 @@ node scripts/mincut-person-counter.js --port 5006  # Correct person counting
 > | **Research NIC** | Intel 5300 / Atheros AR9580 | ~$50-100 | Yes | Full CSI with 3x3 MIMO |
 > | **Any WiFi** | Windows, macOS, or Linux laptop | $0 | No | RSSI-only: coarse presence and motion |
 >
-> No hardware? Verify the signal processing pipeline with the deterministic reference signal: `python v1/data/proof/verify.py`
+> No hardware? Verify the signal processing pipeline with the deterministic reference signal: `python archive/v1/data/proof/verify.py`
 >
 ---
 
@@ -1171,7 +1171,7 @@ Bundle verify:  7/7 checks PASS
 cd v2 && cargo test --workspace --no-default-features
 
 # Run the deterministic proof
-python v1/data/proof/verify.py
+python archive/v1/data/proof/verify.py
 
 # Generate + verify the witness bundle
 bash scripts/generate-witness-bundle.sh
@@ -2164,7 +2164,7 @@ cargo test -p wifi-densepose-sensing-server
 ./target/release/sensing-server --benchmark
 
 # Python tests
-python -m pytest v1/tests/ -v
+python -m pytest archive/v1/tests/ -v
 
 # Pipeline verification (no hardware needed)
 ./verify