Slice 1: scaffolding + propose-to-super-draft vertical

Brings the §1 bot wrapper, the §4 cache (webhook + reconciler), the
§5 schema (six numbered migrations), Gitea OAuth + §6 user
provisioning, the §7 catalog left pane, and the propose-to-merge
vertical: propose modal opens an idea PR against the meta repo, an
owner merges from the pending-idea view, the cache picks it up via
webhook or reconciler sweep, and the catalog renders the new
super-draft.

Per §1 the bot is the only Git writer; every commit, branch
creation, and PR merge carries the §6.5 On-behalf-of: trailer and
an `actions` audit row. Per §4 the cache is never written from a
user action — it's webhook+reconciler only.

Covered by `backend/tests/test_propose_vertical.py` against an
in-process Gitea simulator.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/Landing.jsx

@@ -0,0 +1,24 @@
+// Landing.jsx — §14.1's pre-login surface.
+//
+// Title, subtitle, the short-form pitch from PHILOSOPHY.md, then the
+// single primary action: "Sign in with Gitea." The visual design is
+// deferred per §14.4; the structural commitments are here.
+
+export default function Landing() {
+  return (
+    <div className="landing">
+      <h1>Wiggleverse RFCs</h1>
+      <p className="subtitle">A standards process for shared meaning between humans and machines.</p>
+      <p className="pitch">
+        Large language models work brilliantly with programming languages because every
+        word in Python or C has a definitive meaning enforced by tooling. They struggle
+        with natural language because no such dictionary exists for words like
+        <em> consent</em>, <em> trait</em>, or <em> agency</em> — words that do enormous
+        work in any system that interacts with humans. The Wiggleverse RFC framework is
+        a standardization process for that vocabulary. Build the dictionary first.
+      </p>
+      <a className="btn-signin" href="/auth/login">Sign in with Gitea</a>
+      <a className="secondary-link" href="/philosophy">Read the full philosophy →</a>
+    </div>
+  )
+}