AG-45259 Fix prerelease workflow

Squashed commit of the following:

commit 9729ebc
Author: scripthunter7 <d.tota@adguard.com>
Date:   Mon Dec 15 13:40:03 2025 +0100

    Add shared library build step before type checking in prerelease workflow
    
    - Add explicit build step for @vscode-adblock-syntax/shared package before type checking
    - Ensure shared library is built before dependent packages (client and server) are compiled
    - Prevents type checking failures due to missing shared library build artifacts

Author: totadavid95

bamboo-specs/build-prerelease.yaml

@@ -43,6 +43,9 @@ Build:
             # Install dependencies
             pnpm install
 
+            # Build shared library first (required by client and server)
+            pnpm --filter @vscode-adblock-syntax/shared build
+
             # Check TypeScript types
             pnpm test:compile