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

eleventy.config.js

@@ -0,0 +1,123 @@
+import syntaxHighlight from "@11ty/eleventy-plugin-syntaxhighlight";
+import markdownIt from "markdown-it";
+import markdownItAnchor from "markdown-it-anchor";
+import { DateTime } from "luxon";
+
+export default function (eleventyConfig) {
+  // 1. Static Asset Passthrough Copy
+  eleventyConfig.addPassthroughCopy({ "src/assets": "assets" });
+
+  // 2. Syntax Highlighting Plugin
+  eleventyConfig.addPlugin(syntaxHighlight);
+
+  // 3. Markdown-It Library Customization
+  const markdownOptions = {
+    html: true,
+    breaks: false,
+    linkify: true
+  };
+
+  const markdownLib = markdownIt(markdownOptions).use(markdownItAnchor, {
+    permalink: markdownItAnchor.permalink.headerLink({
+      safariReaderFix: true
+    }),
+    slugify: (s) =>
+      s
+        .trim()
+        .toLowerCase()
+        .replace(/[^a-z0-9 -]/g, "")
+        .replace(/\s+/g, "-")
+        .replace(/-+/g, "-")
+  });
+
+  eleventyConfig.setLibrary("md", markdownLib);
+
+  // 4. Custom Filters
+  // Format readable dates: SEP 12, 2026
+  eleventyConfig.addFilter("postDate", (dateObj) => {
+    if (!dateObj) return "";
+    return DateTime.fromJSDate(new Date(dateObj), { zone: "utc" })
+      .toFormat("LLL dd, yyyy")
+      .toUpperCase();
+  });
+
+  // ISO date format for <time datetime="...">
+  eleventyConfig.addFilter("isoDate", (dateObj) => {
+    if (!dateObj) return "";
+    return DateTime.fromJSDate(new Date(dateObj), { zone: "utc" }).toISODate();
+  });
+
+  // Limit array items
+  eleventyConfig.addFilter("limit", (arr, limit) => {
+    if (!Array.isArray(arr)) return [];
+    return arr.slice(0, limit);
+  });
+
+  // Filter out internal system tags
+  eleventyConfig.addFilter("filterTagList", (tags) => {
+    const internalTags = ["all", "nav", "post", "posts"];
+    return (tags || []).filter((tag) => !internalTags.includes(tag.toLowerCase()));
+  });
+
+  // Reading time estimator (defaults to 200 words/min if frontmatter lacks readingTime)
+  eleventyConfig.addFilter("readingTime", (text, frontmatterTime) => {
+    if (frontmatterTime) return frontmatterTime;
+    if (!text) return "1 MIN READ";
+    const wordCount = text.trim().split(/\s+/).length;
+    const minutes = Math.ceil(wordCount / 200);
+    return `${minutes} MIN READ`;
+  });
+
+  // Extract H2 and H3 headings with IDs for dynamic Table of Contents
+  eleventyConfig.addFilter("extractHeadings", (htmlContent) => {
+    if (!htmlContent) return [];
+    const headingRegex = /<h([23])\s+id="([^"]+)"[^>]*>(.*?)<\/h\1>/gis;
+    const headings = [];
+    let match;
+    while ((match = headingRegex.exec(htmlContent)) !== null) {
+      headings.push({
+        level: parseInt(match[1], 10),
+        id: match[2],
+        title: match[3].replace(/<[^>]+>/g, "").trim()
+      });
+    }
+    return headings;
+  });
+
+  // 5. Custom Collections
+  // Chronological blog posts collection
+  eleventyConfig.addCollection("posts", (collectionApi) => {
+    return collectionApi
+      .getFilteredByGlob("src/posts/*.md")
+      .filter((post) => !post.data.draft)
+      .sort((a, b) => b.date - a.date);
+  });
+
+  // Dynamic Tag List Collection across all posts
+  eleventyConfig.addCollection("tagList", (collectionApi) => {
+    const tagSet = new Set();
+    collectionApi.getFilteredByGlob("src/posts/*.md").forEach((item) => {
+      if ("tags" in item.data) {
+        let tags = item.data.tags;
+        if (typeof tags === "string") tags = [tags];
+        for (const tag of tags) {
+          const cleanTag = tag.replace(/^#/, "");
+          tagSet.add(cleanTag);
+        }
+      }
+    });
+    return [...tagSet].sort();
+  });
+
+  return {
+    dir: {
+      input: "src",
+      includes: "_includes",
+      data: "_data",
+      output: "_site"
+    },
+    templateFormats: ["njk", "md", "html"],
+    htmlTemplateEngine: "njk",
+    markdownTemplateEngine: "njk"
+  };
+}