fix(ci): wrap cross-platform-validation inputs in explicit expressions

Use explicit ${{ }} expression wrapping for job-level if-conditions
that reference github.event.inputs.test_type. GitHub validates
workflow files on push even when the workflow isn't triggered by push,
and bare expressions referencing event inputs may fail validation.

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

Author: docdyhr

.github/workflows/cross-platform-validation.yml

@@ -104,7 +104,7 @@ jobs:
         run: cross build --release --target ${{ matrix.target }}
 
       - name: Run tests (native only)
-        if: matrix.cross == false && (github.event.inputs.test_type || 'full') != 'targets-only'
+        if: ${{ matrix.cross == false && (github.event.inputs.test_type || 'full') != 'targets-only' }}
         run: cargo test --target ${{ matrix.target }} --verbose
 
       - name: Verify binary functionality (native)
@@ -131,7 +131,7 @@ jobs:
   platform-specific-tests:
     name: Platform-Specific Tests
     runs-on: ${{ matrix.os }}
-    if: (github.event.inputs.test_type || 'full') != 'targets-only'
+    if: ${{ (github.event.inputs.test_type || 'full') != 'targets-only' }}
     strategy:
       fail-fast: false
       matrix:
@@ -237,7 +237,7 @@ jobs:
   integration-validation:
     name: Integration Validation
     runs-on: ubuntu-latest
-    if: (github.event.inputs.test_type || 'full') == 'full'
+    if: ${{ (github.event.inputs.test_type || 'full') == 'full' }}
     needs: [cross-compile-targets]
 
     steps: