feat: complete session — catalog, marketplace, WhatsApp, peer-to-peer, install scripts

Major features:
- Pixel-Perfect glassmorphism design (landing + POS + public catalog)
- OEM/Local catalog toggle with Nexpart taxonomy (14 groups, 108 subgroups, 558 part types)
- Marketplace B2B Phase 1 (bodegas, POs, status machine, WA+email notifications)
- Peer-to-peer inventory (multi-instance, LAN discovery)
- WhatsApp: photo→Vision AI, voice→Whisper, conversational quotations
- Smart unified search (VIN/plate/part_number/keyword auto-detect)
- Shop Supplies tab (vehicle-independent parts)
- Chatbot AI fallback chain (5 models) + response cache
- CSV inventory import tool + setup_instance.sh installer
- Tablet-responsive CSS + sidebar toggle
- Filters, export CSV, employee edit, business data save
- Quotation system (WA→POS) with auto-print on confirmation
- Live stats on landing page

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pos/blueprints/peer_bp.py

@@ -0,0 +1,95 @@
+"""
+Peer API — public endpoints for inter-instance communication.
+
+These endpoints do NOT require auth (they're called machine-to-machine by
+other Nexus instances on the network). They expose read-only inventory data
+so the marketplace can aggregate stock across the whole Nexus network.
+
+Routes:
+    GET /pos/api/peer/health        — instance status + inventory count
+    GET /pos/api/peer/inventory     — search this instance's inventory
+"""
+
+from flask import Blueprint, request, jsonify, g
+from tenant_db import get_tenant_conn
+from services import peer_service
+
+peer_bp = Blueprint('peer', __name__, url_prefix='/pos/api/peer')
+
+
+# ─── Which tenant to use for the peer endpoint? ──────────────────────────
+# In production each instance serves one tenant. For the demo, we hardcode
+# tenant_id=11 (the demo refaccionaria). This will be read from a config
+# file in the future when each instance has exactly 1 active tenant.
+
+import os
+import json
+
+def _get_local_tenant_id():
+    """Read the local tenant ID from peers.json or fall back to 11."""
+    try:
+        cfg_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), '..', 'peers.json')
+        with open(cfg_path, 'r') as f:
+            cfg = json.load(f)
+        return cfg.get('tenant_id', 11)
+    except Exception:
+        return 11
+
+
+@peer_bp.route('/health', methods=['GET'])
+def peer_health():
+    """Public health check — no auth. Returns instance name + basic stats."""
+    tenant_id = _get_local_tenant_id()
+    inventory_count = 0
+    try:
+        conn = get_tenant_conn(tenant_id)
+        cur = conn.cursor()
+        cur.execute("""
+            SELECT COUNT(*) FROM inventory i
+            WHERE i.is_active = TRUE
+              AND COALESCE((SELECT SUM(quantity) FROM inventory_operations WHERE inventory_id = i.id), 0) > 0
+        """)
+        inventory_count = cur.fetchone()[0]
+        cur.close()
+        conn.close()
+    except Exception as e:
+        print(f'[peer] health check DB error: {e}')
+
+    return jsonify({
+        'status': 'ok',
+        'instance_name': peer_service.get_instance_name(),
+        'instance_id': peer_service.get_instance_id(),
+        'inventory_count': inventory_count,
+        'peer_count': len(peer_service.get_peers()),
+    })
+
+
+@peer_bp.route('/inventory', methods=['GET'])
+def peer_inventory():
+    """Public inventory search — no auth.
+
+    Called by other Nexus instances to see what this refaccionaria has in stock.
+    Returns minimal data: part number, name, brand, price, stock hint.
+    Does NOT expose exact stock quantities (competitive info).
+
+    Query params:
+        q: search term (optional — without it, returns popular/all items)
+        limit: max results (default 50, max 200)
+    """
+    q = request.args.get('q', '').strip() or None
+    limit = min(request.args.get('limit', 50, type=int), 200)
+
+    tenant_id = _get_local_tenant_id()
+    try:
+        conn = get_tenant_conn(tenant_id)
+        data = peer_service.get_local_inventory(conn, query=q, limit=limit)
+        conn.close()
+    except Exception as e:
+        print(f'[peer] inventory query error: {e}')
+        data = []
+
+    return jsonify({
+        'instance_name': peer_service.get_instance_name(),
+        'data': data,
+        'count': len(data),
+    })