feat(docs): add docs index generator + initial INDEX.md

scripts/generate-docs-index.mjs walks docs/**/*.md, parses YAML
front-matter (or first H1 fallback) and a Nygard-style ## Status
section, then writes docs/INDEX.md with grouped tables for ADRs,
Specs, Plans (with archive subsection), Patterns, and Other.

Pure Node 20 (no external deps); idempotent — running it twice
produces byte-identical output. Excludes adr/templates/, the ADR
README, INDEX.md itself, and any *_*.md sidecar file.

Wire-up:
- package.json: docs:index → node scripts/generate-docs-index.mjs

Initial run indexed 35 docs across the existing structure; the
generated INDEX.md is committed so the table is reviewable in the
PR before hooking generation into a pre-commit step.

docs/INDEX.md

@@ -0,0 +1,65 @@
+<!-- Generated by scripts/generate-docs-index.mjs. Do not edit by hand. Run `npm run docs:index`. -->
+
+# Documentation Index
+
+Auto-generated on 2026-05-02 from front-matter and headings.
+
+## Architecture Decision Records
+
+| # | Title | Status |
+|---|---|---|
+| 0000 | [ADR-0000: Record architecture decisions](./adr/0000-record-architecture-decisions.md) | accepted |
+
+## Specifications
+
+| Title | Status | Updated |
+|---|---|---|
+| [Scrum4Me — Technische Architectuur](./scrum4me-architecture.md) | — | — |
+| [Scrum4Me — Implementatie Backlog](./scrum4me-backlog.md) | — | — |
+| [Scrum4Me — Functionele Specificatie](./scrum4me-functional-spec.md) | — | — |
+| [PbiDialog Profiel](./scrum4me-pbi-dialog.md) | — | — |
+| [DevPlanner — User Personas](./scrum4me-personas.md) | — | — |
+| [DevPlanner — Product Backlog](./scrum4me-product-backlog.md) | — | — |
+| [StoryDialog Profiel](./scrum4me-story-dialog.md) | — | — |
+| [Scrum4Me — Styling & Design System](./scrum4me-styling.md) | — | — |
+| [TaskDialog Profiel](./scrum4me-task-dialog.md) | — | — |
+| [Scrum4Me — API Test Plan](./scrum4me-test-plan.md) | — | — |
+
+## Plans
+
+| Title | Status | Updated |
+|---|---|---|
+| [Docs-restructuur — geoptimaliseerd voor AI-lookup](./plans/docs-restructure-ai-lookup.md) | proposal | 2026-05-02 |
+| [M10 — Password-loze inlog via QR-pairing](./plans/M10-qr-pairing-login.md) | — | — |
+| [M11 — Claude vraagt, gebruiker antwoordt](./plans/M11-claude-questions.md) | — | — |
+| [M9 — Actief Product Backlog](./plans/M9-active-product-backlog.md) | — | — |
+| [Plan — ST-1109 · PBI krijgt een status (Ready / Blocked / Done)](./plans/ST-1109-pbi-status.md) | — | — |
+| [Plan: ST-1110 — Demo gebruiker read-only](./plans/ST-1110-demo-readonly.md) | — | — |
+| [ST-1111 — 'Voer uit'-knop met Claude Code job queue](./plans/ST-1111-claude-job-trigger.md) | — | — |
+| [Plan — ST-1114 · Copilot reviews op dashboard](./plans/ST-1114-copilot-reviews.md) | — | — |
+| [Plan: Tweede Claude Agent — Planning Agent (PBI/Story → children)](./plans/Tweede Claude Agent — Planning Agent.md) | — | — |
+
+## Patterns
+
+| Title | Status | Updated |
+|---|---|---|
+| [Patroon: Bidirectionele async-comms tussen MCP-agent en interactieve user](./patterns/claude-question-channel.md) | — | — |
+| [Pattern — Entity Dialog](./patterns/dialog.md) | — | — |
+| [Patroon: iron-session](./patterns/iron-session.md) | — | — |
+| [Patroon: Proxy (route protection)](./patterns/middleware.md) | — | — |
+| [Patroon: Prisma Client singleton](./patterns/prisma-client.md) | — | — |
+| [Patroon: QR-pairing via unauth-SSE + pre-auth cookie](./patterns/qr-login.md) | — | — |
+| [Patroon: Route Handler (REST API)](./patterns/route-handler.md) | — | — |
+| [Patroon: Server Action](./patterns/server-action.md) | — | — |
+| [Patroon: Float sort_order (drag-and-drop volgorde)](./patterns/sort-order.md) | — | — |
+| [test](./patterns/test.md) | — | — |
+| [Patroon: Zustand optimistische update + rollback](./patterns/zustand-optimistic.md) | — | — |
+
+## Other Docs
+
+| Title | Path | Status | Updated |
+|---|---|---|---|
+| [Agent Instruction Audit](./agent-instruction-audit.md) | `agent-instruction-audit.md` | — | — |
+| [Scrum4Me REST API](./API.md) | `API.md` | — | — |
+| [Material Design 3 Color Scheme Documentation](./MD3_Color_Scheme_Documentation.md) | `MD3_Color_Scheme_Documentation.md` | — | — |
+| [Solo Paneel — Implementatie-specificatie (v2)](./solo-paneel-spec.md) | `solo-paneel-spec.md` | — | — |