feat: initial shared library extraction

Contains shared infrastructure for all coop services:
- shared/ (factory, urls, user_loader, context, internal_api, jinja_setup)
- models/ (User, Order, Calendar, Ticket, Product, Ghost CMS)
- db/ (SQLAlchemy async session, base)
- suma_browser/app/ (csrf, middleware, errors, authz, redis_cacher, payments, filters, utils)
- suma_browser/templates/ (shared base layouts, macros, error pages)
- static/ (CSS, JS, fonts, images)
- alembic/ (database migrations)
- config/ (app-config.yaml)
- editor/ (Lexical editor Node.js build)
- requirements.txt

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

editor/src/index.jsx

@@ -0,0 +1,49 @@
+import React from "react";
+import { createRoot } from "react-dom/client";
+import Editor from "./Editor";
+
+/**
+ * Mount the Koenig editor into the given DOM element.
+ *
+ * @param {string} elementId  - ID of the container element
+ * @param {object} opts
+ * @param {string} [opts.initialJson]     - Serialised Lexical JSON (from Ghost)
+ * @param {string} [opts.csrfToken]       - CSRF token for API calls
+ * @param {object} [opts.uploadUrls]      - { image, media, file } upload endpoint URLs
+ * @param {string} [opts.oembedUrl]       - oEmbed proxy endpoint URL
+ * @param {string} [opts.unsplashApiKey]  - Unsplash API key for image search
+ */
+window.mountEditor = function mountEditor(elementId, opts = {}) {
+  const container = document.getElementById(elementId);
+  if (!container) {
+    console.error(`[editor] Element #${elementId} not found`);
+    return;
+  }
+
+  let currentJson = opts.initialJson || null;
+
+  function handleChange(json) {
+    currentJson = json;
+    // Stash the latest JSON in a hidden input for form submission
+    const hidden = document.getElementById("lexical-json-input");
+    if (hidden) hidden.value = json;
+  }
+
+  const root = createRoot(container);
+  root.render(
+    <Editor
+      initialState={opts.initialJson || null}
+      onChange={handleChange}
+      csrfToken={opts.csrfToken || ""}
+      uploadUrls={opts.uploadUrls || ""}
+      oembedUrl={opts.oembedUrl || "/editor-api/oembed/"}
+      unsplashApiKey={opts.unsplashApiKey || ""}
+      snippetsUrl={opts.snippetsUrl || ""}
+    />
+  );
+
+  // Return handle for programmatic access
+  return {
+    getJson: () => currentJson,
+  };
+};