Monorepo: consolidate 7 repos into one

Combines shared, blog, market, cart, events, federation, and account
into a single repository. Eliminates submodule sync, sibling model
copying at build time, and per-app CI orchestration.

Changes:
- Remove per-app .git, .gitmodules, .gitea, submodule shared/ dirs
- Remove stale sibling model copies from each app
- Update all 6 Dockerfiles for monorepo build context (root = .)
- Add build directives to docker-compose.yml
- Add single .gitea/workflows/ci.yml with change detection
- Add .dockerignore for monorepo build context
- Create __init__.py for federation and account (cross-app imports)

shared/static/labels/_blank.svg

@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     viewBox="0 0 200 200" width="200" height="200" role="img" aria-labelledby="title">
+  <title id="title">Offer ribbon (top-right)</title>
+
+  <!-- Ribbon group: move origin to top-right, then rotate 45° -->
+  <g transform="translate(200 0) rotate(45)">
+    <!-- The stripe -->
+    <rect x="-160" y="50" width="320" height="25" rx="4" fill="#22c55e"/>
+    <!-- Label on the stripe (centered) -->
+    <text x="0" y="65"
+          font-family="system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif"
+          font-size="18" font-weight="800" fill="#ffffff"
+          text-anchor="middle" dominant-baseline="middle" letter-spacing=".15em">
+      NEW
+    </text>
+  </g>
+</svg>

shared/static/labels/new.svg

@@ -0,0 +1,17 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     viewBox="0 0 200 200" width="200" height="200" role="img" aria-labelledby="title">
+  <title id="title">Offer ribbon (top-right)</title>
+
+  <!-- Ribbon group: move origin to top-right, then rotate 45° -->
+  <g transform=" rotate(-45 0 0)">
+    <!-- The stripe -->
+    <rect x="-160" y="25" width="320" height="25" rx="4" fill="#22c55e"/>
+    <!-- Label on the stripe (centered) -->
+    <text x="0" y="40"
+          font-family="system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif"
+          font-size="18" font-weight="800" fill="#ffffff"
+          text-anchor="middle" dominant-baseline="middle" letter-spacing=".15em">
+      NEW
+    </text>
+  </g>
+</svg>

shared/static/labels/offer.svg

@@ -0,0 +1,19 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     viewBox="0 0 200 200" width="200" height="200" role="img" aria-labelledby="title">
+  <title id="title">Offer ribbon</title>
+
+  <!-- Transparent background (nothing drawn) -->
+
+  <!-- Ribbon group rotated -45° around the top-left corner (0,0) -->
+  <g transform="rotate(-45 0 0)">
+    <!-- The stripe itself -->
+    <rect x="-80" y="50" width="260" height="25" rx="4" fill="#ef4444"/>
+    <!-- Centered label on the stripe -->
+    <text x="0" y="65"
+          font-family="system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif"
+          font-size="18" font-weight="800" fill="#ffffff"
+          text-anchor="middle" dominant-baseline="middle" letter-spacing=".15em">
+      OFFER
+    </text>
+  </g>
+</svg>