feat: trade-pro skeleton theme package (Phase 2)

Fifth built-in theme: English-first international B2B skeleton registered
via manifest discovery, builds real sites end-to-end. pro.html derives
from industrial with lang=en, href-set value-comparison English fallback
nav (header + footer), sf-tp-* button classes and hard-coded #0b3d91
theme-color until the map entry lands. pages/ ships all 14 kinds; macro
library is an English passthrough copy pending the Phase 3 cms port.

Co-Authored-By: Claude Code <noreply@anthropic.com>

themes/trade-pro/manifest.json

@@ -0,0 +1,16 @@
+{
+  "id": "trade-pro",
+  "name": "Trade Pro — International B2B",
+  "description": "English-first international B2B theme: responsive trade catalogue, product specs and inquiry CTA.",
+  "version": "1.0.0",
+  "style": "international-b2b",
+  "entry": "pro.html",
+  "styles": ["theme.css", "blocks.css"],
+  "page_templates": ["home","about","contact","listing","category","product","article","brand","case","service","faq","standard","notfound"],
+  "blocks": ["hero","richtext","features","stats","collection","image_text","gallery","faq","cta","attributes","spacer","layout","carousel","video","tabs","pricing","map","form_link"],
+  "responsive": true,
+  "auto_binding": true,
+  "professional_layout": true,
+  "commercial_ui": true,
+  "accent": "#0b3d91"
+}