[ADD] Claude Code ecosystem adapted from Copilot config

Port .github Copilot setup to Claude Code:
- CLAUDE.md: condensed project instructions (auto-loaded each session)
- .claude/skills: per-language guides (odoo-python, odoo-xml-views,
  odoo-qweb-html, odoo-javascript) + openspec-* workflow skills
- .claude/commands/opsx: /opsx:explore|propose|apply|archive slash commands

Original .github/ files kept untouched as extended reference.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.claude/settings.json

@@ -0,0 +1,5 @@
+{
+  "permissions": {
+    "allow": ["Edit(/.claude/skills/odoo-javascript/**)"]
+  }
+}