fix: make sccache optional to handle cache service outages

sccache now gracefully falls back to regular compilation when
GitHub Actions cache service is unavailable.

Changes:
- Remove global RUSTC_WRAPPER env var
- Add continue-on-error to sccache setup
- Only set RUSTC_WRAPPER if sccache is available and working

This prevents build failures during GitHub infrastructure issues.

Author: bumahkib7

.github/workflows/ci.yml

@@ -9,8 +9,6 @@ on:
 env:
   CARGO_TERM_COLOR: always
   RUST_BACKTRACE: 1
-  SCCACHE_GHA_ENABLED: "true"
-  RUSTC_WRAPPER: "sccache"
 
 jobs:
   fmt:
@@ -43,6 +41,13 @@ jobs:
           components: clippy
       - name: Setup sccache
         uses: mozilla-actions/[email protected]
+        continue-on-error: true
+      - name: Configure sccache
+        run: |
+          if command -v sccache &> /dev/null; then
+            echo "SCCACHE_GHA_ENABLED=true" >> $GITHUB_ENV
+            echo "RUSTC_WRAPPER=sccache" >> $GITHUB_ENV
+          fi
       - name: Cache cargo registry
         uses: actions/cache@v4
         with:
@@ -76,6 +81,13 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
       - name: Setup sccache
         uses: mozilla-actions/[email protected]
+        continue-on-error: true
+      - name: Configure sccache
+        run: |
+          if command -v sccache &> /dev/null; then
+            echo "SCCACHE_GHA_ENABLED=true" >> $GITHUB_ENV
+            echo "RUSTC_WRAPPER=sccache" >> $GITHUB_ENV
+          fi
       - name: Cache cargo registry
         uses: actions/cache@v4
         with:
@@ -108,6 +120,13 @@ jobs:
         uses: dtolnay/rust-toolchain@stable
       - name: Setup sccache
         uses: mozilla-actions/[email protected]
+        continue-on-error: true
+      - name: Configure sccache
+        run: |
+          if command -v sccache &> /dev/null; then
+            echo "SCCACHE_GHA_ENABLED=true" >> $GITHUB_ENV
+            echo "RUSTC_WRAPPER=sccache" >> $GITHUB_ENV
+          fi
       - name: Cache cargo registry
         uses: actions/cache@v4
         with:

.github/workflows/release.yml

@@ -11,8 +11,6 @@ permissions:
 
 env:
   CARGO_TERM_COLOR: always
-  SCCACHE_GHA_ENABLED: "true"
-  RUSTC_WRAPPER: "sccache"
 
 jobs:
   build:
@@ -49,6 +47,18 @@ jobs:
       - name: Setup sccache
         if: matrix.use_cross != true
         uses: mozilla-actions/[email protected]
+        continue-on-error: true
+
+      - name: Configure sccache env
+        if: matrix.use_cross != true
+        run: |
+          if command -v sccache &> /dev/null && sccache --version &> /dev/null; then
+            echo "SCCACHE_GHA_ENABLED=true" >> $GITHUB_ENV
+            echo "RUSTC_WRAPPER=sccache" >> $GITHUB_ENV
+          else
+            echo "sccache not available, building without cache"
+          fi
+        shell: bash
 
       - name: Cache cargo registry
         uses: actions/cache@v4