infra(kapsule): upgrade CI build pool from GP1-XS to GP1-L (32 vCPU, 128GB)

Autoscaling pool for CI runner pods — scales to zero when idle.
32 cores dramatically improves parallel Rust compilation times.
Also cleaned up the manually-created ci-build-v2 GP1-S pool.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infra/live/production/kapsule/terragrunt.hcl

@@ -27,6 +27,6 @@ inputs = {
 
   # CI build pool (ephemeral runner pods, scale-to-zero)
   enable_ci_build_pool = true
-  ci_build_type        = "GP1-XS"
+  ci_build_type        = "GP1-L"
   ci_build_max_size    = 2
 }