Initial commit: OpenSpec setup and stock-deep-evaluation change

Set up OpenSpec spec-driven workflow and fully specify the first change,
stock-deep-evaluation: a Next.js/TS app for thorough single-stock
evaluation (valuation reasoning, macro factors, entry/exit points,
stop-loss) with a pluggable data layer and Claude analysis agent.

Includes proposal, design, specs (market-data, equity-evaluation,
analysis-agent, evaluation-app), tasks, and the DE gold-standard example.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,39 @@
+# Dependencies
+node_modules/
+.pnp
+.pnp.js
+.yarn/install-state.gz
+
+# Next.js
+.next/
+out/
+build/
+dist/
+
+# Production
+/coverage
+
+# Environment / secrets (bring-your-own API keys)
+.env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+*.pem
+
+# Logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# Misc / OS
+.DS_Store
+*.tsbuildinfo
+next-env.d.ts
+.vercel
+
+# Editor
+.idea/
+.vscode/*
+!.vscode/extensions.json