fix(ci): exclude subxt crates from umbrella runtime-full to fix wasm32v1-none build

The pez-kitchensink-runtime wasm build was failing because pezkuwi-subxt-signer
(a client-side signing utility) was included in the umbrella's runtime-full
feature. This pulled in regex with workspace-inherited default features (std)
and thiserror v1 which doesn't support no-std, both causing compilation failures
on the wasm32v1-none target.

Changes:
- Exclude pezkuwi-subxt-{signer,core,macro,metadata} from runtime-full in the
  umbrella generator script (they are client-side crates, not runtime crates)
- Fix pezkuwi-subxt-signer's regex dependency to use explicit version with
  default-features=false (Cargo 2021 edition silently ignores default-features
  override with workspace=true when workspace has defaults enabled)
- Add regex/perf to signer's std feature for full performance when std is on

umbrella/Cargo.toml

@@ -1782,10 +1782,6 @@ runtime-full = [
 	"pezkuwi-runtime-common",
 	"pezkuwi-runtime-metrics",
 	"pezkuwi-runtime-teyrchains",
-	"pezkuwi-subxt-core",
-	"pezkuwi-subxt-macro",
-	"pezkuwi-subxt-metadata",
-	"pezkuwi-subxt-signer",
 	"pezkuwi-teyrchain-primitives",
 	"pezpallet-alliance",
 	"pezpallet-asset-conversion",