G1P: vectord persistence to storaged + scrum (3 fixes incl. 3-way convergent)

Adds optional persistence to vectord (G1's HNSW vector search). Single-
file framed format per index — eliminates the torn-write class that
the 3-way convergent scrum finding identified:

  _vectors/<name>.lhv1  — single binary blob:
      [4 bytes magic "LHV1"]
      [4 bytes envelope_len uint32 BE]
      [envelope bytes — JSON params + metadata + version]
      [graph bytes — raw hnsw.Graph.Export]

Pre-extraction: internal/catalogd/store_client.go → internal/storeclient/
shared package, since both catalogd and vectord need it. Same pattern as
the pre-D5 catalogclient extraction.

Optional via [vectord].storaged_url config (empty = ephemeral mode).
On startup: List + Load each persisted index. After Create / batch Add /
DELETE: Save (or Delete from storaged). Save failures are logged-not-
fatal — in-memory state is the source of truth in flight.

Acceptance smoke G1P 8/8 PASS — kill+restart preserves state, post-
restart search returns dist=0 (graph round-trips exactly), DELETE
removes the file, post-delete restart shows count=0.

All 8 smokes (D1-D6 + G1 + G1P) PASS deterministically. The g1_smoke
gained scripts/g1_smoke.toml that disables persistence so the
in-memory API test stays decoupled from any rehydrate-from-storaged
state contamination.

Cross-lineage scrum on shipped code:
  - Opus 4.7 (opencode):                     1 BLOCK + 5 WARN + 3 INFO
  - Kimi K2-0905 (openrouter):               1 BLOCK + 2 WARN
  - Qwen3-coder (openrouter):                2 BLOCK + 2 WARN + 1 INFO

Fixed (3 — 1 convergent + 2 single-reviewer):
  C1 (Opus + Kimi + Qwen 3-WAY CONVERGENT WARN): Save was non-atomic
    across two PUTs — envelope-succeeds + graph-fails left a half-
    saved index that passed the "both present" List filter and
    silently mismatched metadata against vectors on Load.
    Fix: collapse to single framed file (no torn-write window
    possible).
  O-B1 (Opus BLOCK): isNotFound substring-matched "key not found"
    against the wrapped error message — brittle, any 5xx body
    containing that text would silently misclassify as missing.
    Fix: errors.Is(err, storeclient.ErrKeyNotFound).
  O-I3 (Opus INFO): handleAdd pre-validation only covered id+dim;
    NaN/Inf/zero-norm could still fail mid-batch leaving partial
    commits. Fix: extend pre-validation to call ValidateVector
    (newly exported) per item before any commit.

Dismissed (3 false positives):
  K-B1 + Q-B1 ("safeKey double-escapes %2F segments") — false
    convergent. Wire-protocol escape is decoded by storaged's chi
    router on the way in; on-disk key is the original literal.
    %2F round-trips correctly through PathEscape → URL → chi decode
    → S3 key.
  Q-B2 ("List vulnerable to race conditions") — vectord is single-
    process; no concurrent Save against List in the same vectord.

Deferred (3): rehydrate per-index timeout (G2+ multi-index scale),
saveAfter request ctx (matches G0 timeout deferral), Encode RLock
during slow writer (documented as buffer-only API).

The C1 finding is the strongest signal of the cross-lineage filter:
three independent reviewers all flagged the same torn-write hazard.
Single-file framing eliminates the class — there's now no Persistor
state where envelope and graph can disagree.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/g1_smoke.sh

@@ -46,10 +46,10 @@ poll_health() {
 }
 
 echo "[g1-smoke] launching vectord → gateway..."
-./bin/vectord > /tmp/vectord.log 2>&1 &
+./bin/vectord -config scripts/g1_smoke.toml > /tmp/vectord.log 2>&1 &
 PIDS+=($!)
 poll_health 3215 || { echo "vectord failed"; tail /tmp/vectord.log; exit 1; }
-./bin/gateway > /tmp/gateway.log 2>&1 &
+./bin/gateway -config scripts/g1_smoke.toml > /tmp/gateway.log 2>&1 &
 PIDS+=($!)
 poll_health 3110 || { echo "gateway failed"; tail /tmp/gateway.log; exit 1; }
 
@@ -81,14 +81,15 @@ echo "[g1-smoke] add batch of 200 vectors:"
 # Build a batch payload with 200 items. ID encodes index; vector
 # is a deterministic spread so we can assert recall on a known id.
 python3 - <<EOF > "$TMP/batch.json"
-import json, math
+import json
 items = []
 for i in range(200):
-    # Each vector is unit-norm with one dominant axis cycling through 8 dims.
+    # Each vector is unit-norm-ish with one dominant axis cycling
+    # through DIM dims, and a UNIQUE perturbation derived from i itself
+    # (no modulo — would create collisions when 200/DIM rolls over).
     v = [0.0] * $DIM
     v[i % $DIM] = 1.0
-    # Add a tiny perturbation per id so vectors are distinct.
-    v[(i+1) % $DIM] = (i % 17) * 0.01
+    v[(i+1) % $DIM] = i * 0.0001  # unique per i
     items.append({"id": f"w-{i:03d}", "vector": v, "metadata": {"row": i}})
 print(json.dumps({"items": items}))
 EOF
@@ -110,7 +111,7 @@ import json
 i = 42
 v = [0.0] * $DIM
 v[i % $DIM] = 1.0
-v[(i+1) % $DIM] = (i % 17) * 0.01
+v[(i+1) % $DIM] = i * 0.0001  # match the unique-per-i perturbation
 print(json.dumps({"vector": v, "k": 3}))
 EOF
 SEARCH_RESP="$(curl -sS -X POST "http://127.0.0.1:3110/v1/vectors/index/$NAME/search" \