feat: document templates with auto-fill from case data (P1)

- Database: kanzlai.document_templates table with RLS policies
- Seed: 4 system templates (Klageerwiderung UPC, Berufungsschrift,
  Mandatsbestätigung, Kostenrechnung)
- Backend: TemplateService (CRUD + render), TemplateHandler with
  endpoints: GET/POST /api/templates, GET/PUT/DELETE /api/templates/{id},
  POST /api/templates/{id}/render?case_id=X
- Template variables: case.*, party.*, tenant.*, user.*, date.*, deadline.*
- Frontend: /vorlagen page with category filters, template detail/editor,
  render flow (select case -> preview -> copy/download), variable toolbar
- Quick action: "Schriftsatz erstellen" button on case detail page
- Also: resolved merge conflicts between audit-trail and role-based branches,
  added missing Notification/AuditLog types to frontend

backend/internal/auth/context.go

@@ -9,19 +9,11 @@ import (
 type contextKey string
 
 const (
-<<<<<<< HEAD
 	userIDKey    contextKey = "user_id"
 	tenantIDKey  contextKey = "tenant_id"
 	ipKey        contextKey = "ip_address"
 	userAgentKey contextKey = "user_agent"
-||||||| 82878df
-	userIDKey   contextKey = "user_id"
-	tenantIDKey contextKey = "tenant_id"
-=======
-	userIDKey   contextKey = "user_id"
-	tenantIDKey contextKey = "tenant_id"
-	userRoleKey contextKey = "user_role"
->>>>>>> mai/pike/p0-role-based
+	userRoleKey  contextKey = "user_role"
 )
 
 func ContextWithUserID(ctx context.Context, userID uuid.UUID) context.Context {
@@ -41,7 +33,6 @@ func TenantFromContext(ctx context.Context) (uuid.UUID, bool) {
 	id, ok := ctx.Value(tenantIDKey).(uuid.UUID)
 	return id, ok
 }
-<<<<<<< HEAD
 
 func ContextWithRequestInfo(ctx context.Context, ip, userAgent string) context.Context {
 	ctx = context.WithValue(ctx, ipKey, ip)
@@ -62,8 +53,6 @@ func UserAgentFromContext(ctx context.Context) *string {
 	}
 	return nil
 }
-||||||| 82878df
-=======
 
 func ContextWithUserRole(ctx context.Context, role string) context.Context {
 	return context.WithValue(ctx, userRoleKey, role)
@@ -73,4 +62,3 @@ func UserRoleFromContext(ctx context.Context) string {
 	role, _ := ctx.Value(userRoleKey).(string)
 	return role
 }
->>>>>>> mai/pike/p0-role-based