MVP: add mock-first Next.js app shell, AI analysis libs, API routes, DB schema and tests

[dalgme]

Motivation

• Establish a documentation-first, mock-driven MVP for a MarketShield AI global market-entry decision engine and a basic briefing-room UX.
• Provide a minimal-but-complete local end-to-end flow (project creation → orientation → analyses → report preview/export) while keeping real provider/DB integration as future work.
• Enforce structured AI outputs (confidence/rationale/assumptions/limitations) and gated paid features for preview vs full exports.

Description

• Added a Next.js app shell with global styles, layout, pages and UI components including MockReport, PaywallGate, project creation form, orientation, analysis pages, action board and report preview/download flows.
• Implemented API surface and route handlers for AI and analysis flows (normalize-context, run-prompt, orientation/analysis/generate endpoints, project-level read endpoints, failure-pattern matching, and report export with HTML download and PDF disabled).
• Introduced a mock-first AI layer and validators (lib/ai/*): mock/openai provider stubs, prompt runner, system constitution prompts, JSON output validation and context normalizer.
• Implemented analysis/orientation/reporting modules (lib/analysis/*, lib/orientation/*, lib/report/compose.js), a failure-pattern matcher, a local insight pipeline and import script, an in-memory store, a small mock DB helper for client project creation, and billing helpers.
• Added project DB schema and seed files for Supabase (supabase/migrations/..., supabase/seeds/...) and numerous documentation files describing architecture, data strategy, and roadmaps.
• Added scripts and config: package.json, tsconfig.json, next.config.mjs, smoke/unit placeholders and automated test helpers under scripts/ (including smoke-test.js, migration-test.js, import-local-insights.js, and write-stage-report.js).

Testing

• Ran stage validation and smoke tests via npm run validate:stage and npm run test:smoke, and the smoke suite completed successfully printing a full flow verification message.
• Executed migration checks via node scripts/migration-test.js and local-insight import via node scripts/import-local-insights.js, both of which passed (schema/seed checks and sample import succeeded).
• Generated stage report with npm run report:stage -- --stage=16 --ready=yes which wrote the stage report file; lint/typecheck/test/build placeholders were included in the validate flow and returned successful placeholders in CI-local runs.

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Codex Task