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>

suma_browser/app/utils/__init__.py

@@ -0,0 +1,12 @@
+from .parse import (
+  parse_time,
+  parse_cost,
+  parse_dt
+)
+from .utils import (
+  current_route_relative_path,
+  current_url_without_page,
+  vary,
+)
+
+from .utc import utcnow