feat: initial mono-repo with 30 vanity domain sites

Scaffold complete repo structure:
- 28 static sites extracted from running containers on mlake
- 2 dynamic sites (dasbes.de, dumusst.com) marked for separate handling
- Template system with 6 templates (person-dark/light, product-dark, editorial, fun, minimal)
- Shared CSS (variables, responsive, animations, noise overlay)
- nginx config generator with multi-domain alias support
- Build script with Docker-based nginx validation
- add-site.sh helper for scaffolding new domains
- Dockerfile for single nginx:alpine container

Sites: clemensplassmann.de, danosi.de, deinesei.de, derkaiseristnackt.de,
elefantenhor.de, fragina.de, frenchkis.de, ichbinaufbali.de, ichbinaufbarley.de,
insain.de, julietensity.de, kainco.de (+keinco.de), kainstress.de, keinefreun.de,
knzlmgmt.de, kopffrai.de, legalais.de, machesdocheinfach.de, mai-otto.de
(+otto.flexsiebels.de, ottomatisch.de, ichbinotto.de), martinsiebels.de,
matthiasbreier.de, osterai.de, paragraphenraiter.de, schulfrai.de, smartin3.de,
sorgenfrai.de, vonschraitter.de, wartebitte.de

Refs: otto#341

README.md

@@ -1,3 +1,91 @@
 # onepager
 
-Mono-repo for 40+ vanity domain onepager sites — single nginx container with template system
+Mono-repo for 40+ vanity domain onepager sites. Single nginx container with template system and server_name-based routing.
+
+## Structure
+
+```
+sites/           # One folder per domain
+  example.de/
+    site.yaml    # Domain config, template choice, variables
+    index.html   # Content (generated or hand-crafted)
+    assets/      # Optional images, fonts
+templates/       # Shared HTML templates
+shared/css/      # Shared CSS (variables, responsive, animations)
+nginx/           # Generated nginx.conf + generator script
+build/           # Generated output (gitignored)
+```
+
+## Usage
+
+### Add a new site
+
+```bash
+# Templated site
+./add-site.sh example.de --template person-dark --name "Max Mustermann"
+
+# Custom HTML site
+./add-site.sh example.de --template custom
+```
+
+### Build
+
+```bash
+./build.sh
+```
+
+Requires `yq` for YAML parsing. Outputs to `build/` directory.
+
+### Deploy
+
+Push to main — Dokploy auto-deploys. All domains must be configured in Dokploy.
+
+## Templates
+
+| Template | Description |
+|----------|-------------|
+| `person-dark` | Professional profile, dark theme |
+| `person-light` | Professional profile, light/cream theme |
+| `product-dark` | Product/service landing page, dark |
+| `editorial` | Long-form manifesto/editorial style |
+| `fun` | Playful/personal pages |
+| `minimal` | Bare-bones single section |
+| `custom` | Hand-crafted HTML, no rendering |
+
+## site.yaml
+
+```yaml
+domain: example.de
+aliases: [www.example.de]
+template: person-dark
+title: "Page Title"
+description: "Meta description"
+lang: de
+
+vars:
+  name: "Name"
+  role: "Role"
+  initials: "AB"
+  tagline: "Tagline here"
+  accent: "#c9a84c"
+  accent_light: "rgba(201, 168, 76, 0.1)"
+  font_primary: "Inter"
+  font_secondary: "Newsreader"
+  tags: ["Tag 1", "Tag 2"]
+  sections:
+    - type: features
+      title: "Section Title"
+      items:
+        - title: "Item"
+          desc: "Description"
+    - type: profile
+      bio: "Bio text"
+  cta:
+    text: "Contact"
+    href: "mailto:info@example.de"
+```
+
+## Related
+
+- Issue #341: Onepager Mono-Repo
+- Issue #335: Container consolidation