feat: initial llm-connect package scaffold

Copy markitect.llm module into standalone llm_connect package.
All markitect.* imports replaced with llm_connect.* equivalents.
LLMError base class inlined (no markitect.exceptions dependency).
Verified: from llm_connect import create_adapter works.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,21 @@
+[build-system]
+requires = ["setuptools>=68", "wheel"]
+build-backend = "setuptools.backends.legacy:build"
+
+[project]
+name = "llm-connect"
+version = "0.1.0"
+description = "Pluggable LLM adapters for OpenRouter, Gemini, OpenAI and Claude Code CLI"
+requires-python = ">=3.10"
+dependencies = [
+    "toml",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=7.0",
+]
+
+[tool.setuptools.packages.find]
+where = ["."]
+include = ["llm_connect*"]