feat: implement dynamic Eleventy tiling blog, modular CSS, and agent customizations

- Add project foundation README.md and root AGENTS.md for pair programming
- Configure .agents/ rules and skills for Eleventy tiling and Obsidian publishing
- Decompose monolithic styles into modular tokens, reset, layout, and component CSS
- Implement Nunjucks layout inheritance (base.njk, post.njk, page.njk) and reusable partials
- Configure Eleventy 3 with markdown-it-anchor, syntax highlighting, and dynamic collections
- Migrate sample prototypes into dynamic dispatches lander, gateway, and Markdown posts
- Add multi-stage Dockerfile and clean-URL nginx.conf for production serving

src/assets/css/tokens.css

@@ -0,0 +1,38 @@
+/* ==========================================================================
+   Design Tokens (tokens.css)
+   River Rooks Blog - Native Dark Mode Architecture
+   ========================================================================== */
+
+:root {
+  /* Surface & Canvas Colors */
+  --bg-canvas: #0d0f12;      /* Deep slate/charcoal canvas */
+  --bg-surface: #121417;     /* Tile & card surface */
+  --bg-elevated: #1c1f26;    /* Hovered surface */
+  
+  /* Borders & Dividers */
+  --border-color: #2b303b;   /* Crisp 1px border */
+  --border-width: 1px;
+  --border-radius: 4px;      /* Strictly capped at 4px */
+  --border-radius-sm: 2px;
+  --border-radius-xs: 1px;
+
+  /* Typography */
+  --font-mono: 'IBM Plex Mono', 'JetBrains Mono', monospace;
+  --font-code: 'JetBrains Mono', 'Fira Code', monospace;
+  --font-prose: 'Inter', system-ui, -apple-system, sans-serif;
+
+  /* Text Colors */
+  --text-primary: #e0e6f0;   /* Light off-white prose */
+  --text-muted: #8a95a5;     /* Monospace metadata */
+
+  /* High-Signal Terminal Accents */
+  --accent-cyan: #00f0ff;    /* Primary active accent */
+  --accent-green: #00e676;   /* Success / online indicator */
+  --accent-amber: #ffb700;   /* Warning / highlight accent */
+  --accent-red: #ff5252;     /* Danger / caution accent */
+
+  /* Structural Dimensions */
+  --site-max-width: 1140px;
+  --tile-gap: 16px;
+  --prose-max-width: 68ch;
+}