feat: public template catalog + Vercel git integration

Backend: service_templates.is_public lets owners publish user templates to
the anonymous catalog (GET /api/v1/templates), mirroring Railway's
marketplace publish flow. Migration, sqlc queries, visibility rules, and
openapi.yaml updated; types regenerated.

App: template editor gains a "List in the public catalog" checkbox;
Public badge on catalog cards and detail view.

Site: new templates.html catalog page - search, category filters, Official
vs Community badges, detail modal with variables and copyable import JSON.
Fetches the live catalog from a reachable instance (?api= or localStorage
override) and falls back to templates.json, generated from SeedTemplates
via cmd/dumptemplates. Shared styles extracted to style.css.

Vercel: project connected to GitHub repo with rootDirectory=site;
.vercelignore limits CLI uploads to site/ so `vercel deploy --prod` from
repo root matches git builds.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/frontend/src/lib/api-client.ts

@@ -124,6 +124,7 @@ export type TemplateEntity = {
   variablesRaw: string;
   isOfficial: boolean;
   ownerId: string | null;
+  isPublic: boolean;
   createdAt?: string;
   updatedAt?: string;
 };
@@ -615,6 +616,7 @@ function normalizeTemplate(template: RawServiceTemplate): TemplateEntity | null
     variablesRaw: template.variables ?? '',
     isOfficial: Boolean(template.is_official),
     ownerId: template.owner_id ?? null,
+    isPublic: Boolean(template.is_public),
     createdAt: template.created_at,
     updatedAt: template.updated_at,
   };
@@ -1358,6 +1360,7 @@ export type TemplateWriteInput = {
   logo?: string;
   config: Record<string, unknown>;
   variables?: TemplateVariableEntity[];
+  isPublic?: boolean;
 };
 
 function templateWriteBody(input: TemplateWriteInput): string {
@@ -1368,6 +1371,7 @@ function templateWriteBody(input: TemplateWriteInput): string {
     logo: input.logo ?? '',
     config: input.config,
     variables: input.variables ?? [],
+    is_public: input.isPublic ?? false,
   });
 }