feat: add Supabase schema, edge functions, and SQL views

Telemetry backend infrastructure: telemetry_events table with RLS
(insert-only), installations table for retention tracking,
update_checks for install pings. Edge functions for update-check
(version + ping), telemetry-ingest (batch insert), and
community-pulse (weekly active count). SQL views for crash
clustering and skill co-occurrence sequences.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

supabase/functions/update-check/index.ts

@@ -0,0 +1,37 @@
+// gstack update-check edge function
+// Logs an install ping and returns the current latest version.
+// Called by bin/gstack-update-check as a parallel background request.
+
+import { createClient } from "https://esm.sh/@supabase/supabase-js@2";
+
+const CURRENT_VERSION = Deno.env.get("GSTACK_CURRENT_VERSION") || "0.6.4.1";
+
+Deno.serve(async (req) => {
+  if (req.method !== "POST") {
+    return new Response(CURRENT_VERSION, { status: 200 });
+  }
+
+  try {
+    const { version, os } = await req.json();
+
+    if (!version || !os) {
+      return new Response(CURRENT_VERSION, { status: 200 });
+    }
+
+    const supabase = createClient(
+      Deno.env.get("SUPABASE_URL") ?? "",
+      Deno.env.get("SUPABASE_SERVICE_ROLE_KEY") ?? ""
+    );
+
+    // Log the update check (fire-and-forget)
+    await supabase.from("update_checks").insert({
+      gstack_version: String(version).slice(0, 20),
+      os: String(os).slice(0, 20),
+    });
+
+    return new Response(CURRENT_VERSION, { status: 200 });
+  } catch {
+    // Always return the version, even if logging fails
+    return new Response(CURRENT_VERSION, { status: 200 });
+  }
+});