ci(test): make the broad dry-run matrix all-required (no optional legs)

The release dry run must be all-green on every platform — drop the
optional/continue-on-error flags from the broad matrix legs (ubuntu-22.04,
ubuntu-22.04-arm, macos-15, windows-2025) so a failure on any of them gates
the run. Only affects broad_platforms=true (the dry run); the core PR-CI
matrix is unchanged.

Signed-off-by: Martin Vogel <martin.vogel.tech@gmail.com>

Author: DeusData

.github/workflows/_test.yml

@@ -38,10 +38,12 @@ jobs:
             {"os":"macos-14","cc":"cc","cxx":"c++"},
             {"os":"macos-15-intel","cc":"cc","cxx":"c++"}
           ]'
+          # Broad matrix legs are REQUIRED gates (no optional/continue-on-error
+          # escape hatches): the release dry run must be all-green, every platform.
           BROAD_UNIX='[
-            {"os":"ubuntu-22.04","cc":"gcc","cxx":"g++","optional":true},
-            {"os":"ubuntu-22.04-arm","cc":"gcc","cxx":"g++","optional":true},
-            {"os":"macos-15","cc":"cc","cxx":"c++","optional":true}
+            {"os":"ubuntu-22.04","cc":"gcc","cxx":"g++"},
+            {"os":"ubuntu-22.04-arm","cc":"gcc","cxx":"g++"},
+            {"os":"macos-15","cc":"cc","cxx":"c++"}
           ]'
           # Each Windows leg pins the msys2 environment + package arch to the
           # RUNNER architecture so the build is native, never emulated:
@@ -53,7 +55,7 @@ jobs:
           # the native ARM64 toolchain ASan instruments native ARM64 code, so it
           # is a real (non-optional) gate, not a tolerated emulated-flake.
           CORE_WIN='[{"os":"windows-latest","msystem":"CLANG64","pkg":"x86_64"}]'
-          BROAD_WIN='[{"os":"windows-2025","optional":true,"msystem":"CLANG64","pkg":"x86_64"},{"os":"windows-11-arm","msystem":"CLANGARM64","pkg":"aarch64"}]'
+          BROAD_WIN='[{"os":"windows-2025","msystem":"CLANG64","pkg":"x86_64"},{"os":"windows-11-arm","msystem":"CLANGARM64","pkg":"aarch64"}]'
           if [ "$BROAD" = "true" ]; then
             UNIX=$(jq -cn --argjson a "$CORE_UNIX" --argjson b "$BROAD_UNIX" '$a + $b')
             WIN=$(jq -cn --argjson a "$CORE_WIN" --argjson b "$BROAD_WIN" '$a + $b')