ci: switch workflows to lux-build (luxfi-scoped ARC pool)

Cross-org runs-on dispatch failure: hanzo-build-linux-amd64 scale set is
registered to github.com/hanzoai and silently rejects luxfi/* jobs.
Switch to lux-build (githubConfigUrl=github.com/luxfi, max 20).

.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
         # cross-compiled (build only) in the `build` job below.
         arch: [amd64]
         cgo: ['0', '1']
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -64,7 +64,7 @@ jobs:
 
   hqc-pqclean-e2e:
     name: HQC PQClean cgo e2e (NIST KAT roundtrip)
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -84,7 +84,7 @@ jobs:
         arch: [amd64, arm64]
     # All builds run on the amd64 self-hosted runner. arm64 cross-compiles
     # via GOARCH; CGO_ENABLED=0 keeps it pure-Go (no cross-compiler needed).
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5

.github/workflows/release.yml

@@ -19,7 +19,7 @@ jobs:
       # via cross-compile in the `build` job below.
       matrix:
         arch: [amd64]
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -36,7 +36,7 @@ jobs:
         arch: [amd64, arm64]
     # All builds run on the amd64 self-hosted runner. arm64 cross-compiles
     # via GOARCH; CGO_ENABLED=0 keeps it pure-Go (no cross-compiler needed).
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -51,7 +51,7 @@ jobs:
 
   release:
     needs: build
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
         with:

.github/workflows/test.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         arch: [amd64]
         cgo: ['0', '1']
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-go@v5
@@ -29,7 +29,7 @@ jobs:
   # Slower than native (5-10x) but functional for arm64 regression catching.
   go-arm64-emulated:
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     steps:
       - uses: actions/checkout@v4
       - name: Set up QEMU
@@ -50,7 +50,7 @@ jobs:
       # Same constraint: cargo test must execute on the build host's arch.
       matrix:
         arch: [amd64]
-    runs-on: hanzo-build-linux-amd64
+    runs-on: lux-build
     defaults:
       run:
         working-directory: rust