feat: Sharp style, Tailwind+shadcn, dark navbar, nav restructure, Go/monorepo guidelines

Styling:
- Tailwind CSS v4 (preflight:false) integrated via PostCSS plugin
- shadcn/ui New York style with --radius:0 (sharp corners everywhere)
- Zero border-radius on ALL elements: buttons, code blocks, cards, admonitions, badges
- Navbar FORCE dark (#0a0a0a) in both light/dark modes via !important
- ThemeSynchronizer: bridges Docusaurus data-theme → shadcn .dark class
- Active sidebar item gets left border accent instead of rounded bg

React UI components (src/components/ui/index.tsx):
- Badge (6 variants: wip, stable, planned, success, warning, outline)
- Card + CardHeader + CardTitle + CardContent
- Callout (note/info/success/warning/danger) - sharp, left-border style
- PropertiesTable - monospace typed API reference tables
- StatusIndicator - operational/degraded/outage/maintenance

Navigation restructure:
- Introduction → Platform → Products → Engineering → Runbooks
- Old 'applications/' removed, moved to products/stock-market-pro/
- New Platform section: infrastructure overview + CI/CD pipeline docs
- New Engineering section: monorepo structure, Go stack, conventions
- New Runbooks section: incident severity, common procedures

Implementation guidelines (engineering/guidelines.md):
- Monorepo layout with go.work workspace
- Go as primary language (why + standard library table)
- Python as sidecar for data/ML workloads
- Code conventions: gofmt, error wrapping, logging, testing
- Git conventions: branch naming, conventional commits
- Makefile targets per app
- How to add a new application (step-by-step)

docs/intro/index.md

@@ -3,29 +3,46 @@ sidebar_position: 1
 slug: /intro
 ---
 
-# SKIC Playground Documentation
+# SKIC Platform
 
-Welcome to the documentation hub for **SKIC Playground** — a collection of autonomous applications built and maintained by Jarvis (AI agent).
+**SKIC Playground** is a self-hosted autonomous platform — a collection of applications designed, built, and operated by Jarvis (AI agent) on top of a private infrastructure stack.
 
-## What is this?
+## What lives here
 
-This documentation covers various applications designed, developed, and operated autonomously. Each application has its own section with:
+import { Badge, Card, CardHeader, CardTitle, CardContent } from '@site/src/components/ui';
 
-- **Overview** — What the application does and why
-- **Architecture** — Technical design decisions and system diagrams
-- **Configuration** — How to set up and configure
-- **Operations** — How the application runs day-to-day
+<div className="grid grid-cols-1 gap-3 my-6">
+  <Card>
+    <CardHeader>
+      <div className="flex items-center justify-between">
+        <CardTitle>📈 Stock Market Professional</CardTitle>
+        <Badge variant="wip">In Development</Badge>
+      </div>
+    </CardHeader>
+    <CardContent>
+      Monitors forex & stock markets, applies technical analysis to spot patterns, and emits daily trading signals (max 3 positions, 30-minute hold, manual execution).
+    </CardContent>
+  </Card>
+</div>
 
-## Applications
+## How this documentation is structured
 
-| Application | Status | Description |
-|---|---|---|
-| [Stock Market Professional](../applications/stock-market-professional/index.md) | 🚧 In Development | Forex/stock monitoring, technical analysis, and signal generation |
+| Section | Contents |
+|---|---|
+| **Introduction** | This page — platform overview and navigation guide |
+| **Platform** | Infrastructure, CI/CD, networking, auth |
+| **Products** | Each autonomous application — architecture, modules, operations |
+| **Engineering** | Development conventions, monorepo structure, tech stack |
+| **Runbooks** | Operational procedures, incident response, diagnostics |
 
-## Technology Stack
+## Technology at a glance
 
-- **Infrastructure**: TrueNAS SCALE, Gitea, Docker
-- **CI/CD**: Gitea Actions
-- **Documentation**: Docusaurus + pnpm
-- **Languages**: TypeScript, Python
-- **AI/ML**: Pattern recognition, technical analysis algorithms
+| Layer | Technology |
+|---|---|
+| Infrastructure | TrueNAS SCALE, Docker, Gitea |
+| Auth | Keycloak (SSO) |
+| Registry | Zot (OCI) |
+| CI/CD | Gitea Actions |
+| App language | Go (services), Python (data/analysis), TypeScript (frontend) |
+| Docs | Docusaurus v3 + pnpm + Tailwind + shadcn/ui |
+| AI operations | Hermes Agent (Jarvis) |