fix: shellcheck SC2001 and SC2015 in claude workflow

Replace sed prompt extraction with parameter expansion (SC2001).

Author: enitrat

.github/workflows/claude.yml

@@ -107,22 +107,20 @@ jobs:
       - name: Exchange OIDC for GitHub App token
         id: oidc-exchange
         run: |
-          OIDC_RESPONSE=$(curl -s \
+          OIDC_TOKEN=$(curl -sf \
             -H "Authorization: bearer $ACTIONS_ID_TOKEN_REQUEST_TOKEN" \
-            "$ACTIONS_ID_TOKEN_REQUEST_URL&audience=claude-code-github-action")
-          OIDC_TOKEN=$(echo "$OIDC_RESPONSE" | jq -r '.value')
+            "$ACTIONS_ID_TOKEN_REQUEST_URL&audience=claude-code-github-action" | jq -r '.value')
           if [ -z "$OIDC_TOKEN" ] || [ "$OIDC_TOKEN" = "null" ]; then
-            echo "::error::OIDC token request failed: $OIDC_RESPONSE"; exit 1
+            echo "::error::OIDC token request failed"; exit 1
           fi
 
-          EXCHANGE_RESPONSE=$(curl -s -X POST \
+          APP_TOKEN=$(curl -sf -X POST \
             -H "Authorization: Bearer $OIDC_TOKEN" \
             -H "Content-Type: application/json" \
             -d '{"permissions":{"contents":"write","pull_requests":"write","issues":"write"}}' \
-            "https://api.anthropic.com/api/github/github-app-token-exchange")
-          APP_TOKEN=$(echo "$EXCHANGE_RESPONSE" | jq -r '.token')
+            "https://api.anthropic.com/api/github/github-app-token-exchange" | jq -r '.token')
           if [ -z "$APP_TOKEN" ] || [ "$APP_TOKEN" = "null" ]; then
-            echo "::error::Token exchange failed: $EXCHANGE_RESPONSE"; exit 1
+            echo "::error::Token exchange failed"; exit 1
           fi
 
           echo "::add-mask::$APP_TOKEN"
@@ -233,7 +231,7 @@ jobs:
           claude plugin install zama-developer@zama-marketplace
 
           # Extract prompt: everything after "@claude" in the comment
-          PROMPT=$(echo "$COMMENT_BODY" | sed 's/.*@claude[[:space:]]*//')
+          PROMPT=${COMMENT_BODY#*@claude }
 
           claude -p "$PROMPT" \
             --model opus \
@@ -271,8 +269,8 @@ jobs:
       - name: Revoke GitHub App token
         if: always() && steps.oidc-exchange.outputs.app_token != ''
         run: |
-          REVOKE_OUTPUT=$(gh api "installation/token" -X DELETE 2>&1) || {
-            echo "::warning::Token revocation failed: $REVOKE_OUTPUT"
+          gh api "installation/token" -X DELETE || {
+            echo "::warning::Token revocation failed"
           }
         env:
           GH_TOKEN: ${{ steps.oidc-exchange.outputs.app_token }}