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).

.github/workflows/verify-pipeline.yml

@@ -4,16 +4,16 @@ on:
   push:
     branches: [ main, master, 'claude/**' ]
     paths:
-      - 'v1/src/core/**'
-      - 'v1/src/hardware/**'
-      - 'v1/data/proof/**'
+      - 'archive/v1/src/core/**'
+      - 'archive/v1/src/hardware/**'
+      - 'archive/v1/data/proof/**'
       - '.github/workflows/verify-pipeline.yml'
   pull_request:
     branches: [ main, master ]
     paths:
-      - 'v1/src/core/**'
-      - 'v1/src/hardware/**'
-      - 'v1/data/proof/**'
+      - 'archive/v1/src/core/**'
+      - 'archive/v1/src/hardware/**'
+      - 'archive/v1/data/proof/**'
       - '.github/workflows/verify-pipeline.yml'
   workflow_dispatch:
 
@@ -37,19 +37,19 @@ jobs:
       - name: Install pinned dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install -r v1/requirements-lock.txt
+          pip install -r archive/v1/requirements-lock.txt
 
       - name: Verify reference signal is reproducible
         run: |
           echo "=== Regenerating reference signal ==="
-          python v1/data/proof/generate_reference_signal.py
+          python archive/v1/data/proof/generate_reference_signal.py
           echo ""
           echo "=== Checking data file matches committed version ==="
           # The regenerated file should be identical to the committed one
           # (We compare the metadata file since data file is large)
           python -c "
           import json, hashlib
-          with open('v1/data/proof/sample_csi_meta.json') as f:
+          with open('archive/v1/data/proof/sample_csi_meta.json') as f:
               meta = json.load(f)
           assert meta['is_synthetic'] == True, 'Metadata must mark signal as synthetic'
           assert meta['numpy_seed'] == 42, 'Seed must be 42'
@@ -76,7 +76,7 @@ jobs:
           echo "=== Scanning for unseeded np.random usage in production code ==="
           # Search for np.random calls without a seed in production code
           # Exclude test files, proof data generators, and known parser placeholders
-          VIOLATIONS=$(grep -rn "np\.random\." v1/src/ \
+          VIOLATIONS=$(grep -rn "np\.random\." archive/v1/src/ \
             --include="*.py" \
             --exclude-dir="__pycache__" \
             | grep -v "np\.random\.RandomState" \