fix(skills): update neuledge-context with session lessons

- Fix claude mcp add scope flag: -s user for global, -s project for
  per-project --libs (--project flag does not exist)
- Project scope writes to .mcp.json (committed); not settings.local.json
- Document dual-scope pattern and expected conflict warning
- Document MCP tools not available mid-session after claude mcp add;
  require /reload-plugins or new session
- Expand context add step with llms.txt-first workflow for registry gaps
  (Anthropic, Claude Code, MCP docs not in public registry)
- Fix self-check: explicit scope flag required, context list for identifiers
- Add .mcp.json with project-scoped context serve --libs for this repo

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TP4EGbBg3XMcyF28Lx78XJ

.mcp.json

@@ -0,0 +1,18 @@
+{
+  "mcpServers": {
+    "context": {
+      "type": "stdio",
+      "command": "context",
+      "args": [
+        "serve",
+        "--libs",
+        "claude-code-docs",
+        "mcp-docs",
+        "agent-skills-standard",
+        "github-copilot-docs",
+        "openai-agents-sdk"
+      ],
+      "env": {}
+    }
+  }
+}