Add AI Harness And Restructure Documentation

[Cynthion]

What

The repository gets a Claude Code harness, with an fd- prefix: path-scoped rules, four SDD agents, eight skills and four MCP servers. The documentation gains a Definition of Done, a developer onboarding and one convention document per area, and is audited against the new documentation guidelines, which a Markdown lint gate now enforces.

Why

Spec Driven Development with an explicit Definition of Done, conventions an agent loads only for the files it touches, and documentation whose links and style are checked rather than reviewed.

Notes

• Docs Split: impl/conventions.md became components.md, typescript.md, styling.md, ubiquitous-language.md and definition-of-done.md; impl/claude-code.md became ai-harness.md; portal.md moved to tech/. No content was dropped.
• Links: file references are Markdown links now, so the portal's linkFileReferences workaround and its three specs are deleted.
• Permissions: the repository is public, so .claude/settings.json only approves MCP servers; permissions are personal in .claude/settings.local.json.
• CI: new Lint Markdown step; Test Demo and Build Demo renamed to Portal.

Developer Actions

Action	Reason
npm install	New dev dependencies markdownlint-cli2 and its links rule
export CONTEXT7_API_KEY=…	The context7 MCP server, see impl/developer-onboarding.md
Create .claude/settings.local.json with the denies	Recommended baseline under Permissions in impl/ai-harness.md

Verification

Gate	Result
npm run docs:lint	Pass
npm run prettier:check	Pass
npm run lint, npm run style-lint	Pass
npm run docs:check	Pass
npm run build:lib	Pass
Library tests	571/571
Portal tests	227/227
npm run build	Pass