perf: optimize Squid proxy startup time (#334)

* perf: optimize Squid proxy startup time

- Replace fixed 7-second sleep with dynamic readiness check
- Only shutdown existing Squid if actually running
- Add detailed timing logs to track each step's duration
- Expected reduction: ~7-8 seconds to ~1-2 seconds startup overhead

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* refactor: extract squid setup into standalone script

Move squid proxy setup logic from action.yml inline bash script
to scripts/setup-network-restrictions.sh for better maintainability
and cleaner action configuration.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* Revert "refactor: extract squid setup into standalone script"

This reverts commit b18aa2821d.

* tmp

* Reapply "refactor: extract squid setup into standalone script"

This reverts commit 07f6911549.

---------

Co-authored-by: Claude <noreply@anthropic.com>

action.yml

@@ -155,50 +155,34 @@ runs:
         ADDITIONAL_PERMISSIONS: ${{ inputs.additional_permissions }}
         USE_COMMIT_SIGNING: ${{ inputs.use_commit_signing }}
 
+    - name: Install Base Action Dependencies
+      if: steps.prepare.outputs.contains_trigger == 'true'
+      shell: bash
+      run: |
+        echo "Installing base-action dependencies..."
+        cd ${GITHUB_ACTION_PATH}/base-action
+        bun install
+        echo "Base-action dependencies installed"
+        cd -
+        # Install Claude Code globally
+        bun install -g @anthropic-ai/claude-code@1.0.59
+
     - name: Setup Network Restrictions
       if: steps.prepare.outputs.contains_trigger == 'true' && inputs.experimental_allowed_domains != ''
       shell: bash
       run: |
-        # Install and configure Squid proxy
-        sudo apt-get update && sudo apt-get install -y squid
-
-        echo "${{ inputs.experimental_allowed_domains }}" > $RUNNER_TEMP/whitelist.txt
-
-        # Configure Squid
-        sudo tee /etc/squid/squid.conf << EOF
-        http_port 127.0.0.1:3128
-        acl whitelist dstdomain "$RUNNER_TEMP/whitelist.txt"
-        acl localhost src 127.0.0.1/32
-        http_access allow localhost whitelist
-        http_access deny all
-        cache deny all
-        EOF
-
-        # Stop any existing squid instance and start with our config
-        sudo squid -k shutdown || true
-        sleep 2
-        sudo rm -f /run/squid.pid
-        sudo squid -N -d 1 &
-        sleep 5
-
-        # Set proxy environment variables
-        echo "http_proxy=http://127.0.0.1:3128" >> $GITHUB_ENV
-        echo "https_proxy=http://127.0.0.1:3128" >> $GITHUB_ENV
-        echo "HTTP_PROXY=http://127.0.0.1:3128" >> $GITHUB_ENV
-        echo "HTTPS_PROXY=http://127.0.0.1:3128" >> $GITHUB_ENV
+        chmod +x ${GITHUB_ACTION_PATH}/scripts/setup-network-restrictions.sh
+        ${GITHUB_ACTION_PATH}/scripts/setup-network-restrictions.sh
+      env:
+        EXPERIMENTAL_ALLOWED_DOMAINS: ${{ inputs.experimental_allowed_domains }}
 
     - name: Run Claude Code
       id: claude-code
       if: steps.prepare.outputs.contains_trigger == 'true'
       shell: bash
       run: |
-        # Install Claude Code globally
-        bun install -g @anthropic-ai/claude-code@1.0.59
 
         # Run the base-action
-        cd ${GITHUB_ACTION_PATH}/base-action
-        bun install
-        cd -
         bun run ${GITHUB_ACTION_PATH}/base-action/src/index.ts
       env:
         # Base-action inputs