feat(scaffold): S5 — D7 sibling scaffold: SDK dep, fail-fast startup contracts, CLAUDE.md

Claude Agent SDK verified against official docs + PyPI 2026-07-03 (0.2.110, CLI
bundled, offline import without API key). Contracts mirror method-spec §10/§4.1/§8:
data-source, model-map (per-profile default required), termination (positive caps),
binary feedback decision. TDD: tests written red-first; suite 14/14 green without
any API key; ruff + mypy --strict clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AaQCFnfsh3tfq1VfzdJpoi

pyproject.toml

@@ -0,0 +1,34 @@
+[project]
+name = "portfolio-optimiser-claude"
+version = "0.1.0"
+description = "Sibling implementation of the portfolio-optimiser method on the Claude Agent SDK (D7)"
+readme = "README.md"
+requires-python = ">=3.10"
+dependencies = [
+    "claude-agent-sdk>=0.2",
+    "pydantic>=2",
+]
+
+[dependency-groups]
+dev = [
+    "pytest>=8",
+    "ruff>=0.8",
+    "mypy>=1.13",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/portfolio_optimiser_claude"]
+
+[tool.ruff]
+line-length = 100
+target-version = "py310"
+
+[tool.mypy]
+strict = true
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]