feat(tools): add web_search_tool for internet search

Add native web search capability that works regardless of LLM tool-calling
support. This is particularly useful for GLM models via Z.AI that don't
reliably support standard tool calling formats.

Features:
- DuckDuckGo provider (free, no API key required)
- Brave Search provider (optional, requires API key)
- Configurable max results and timeout
- Enabled by default

Configuration (config.toml):
  [web_search]
  enabled = true
  provider = "duckduckgo"
  max_results = 5

The tool allows agents to search the web for current information without
requiring proper tool calling support from the LLM.

Also includes CI workflow fix for first-interaction action inputs.

.github/workflows/pr-auto-response.yml

@@ -40,8 +40,8 @@ jobs:
       - name: Greet first-time contributors
         uses: actions/first-interaction@a1db7729b356323c7988c20ed6f0d33fe31297be # v1
         with:
-          repo-token: ${{ secrets.GITHUB_TOKEN }}
-          issue-message: |
+          repo_token: ${{ secrets.GITHUB_TOKEN }}
+          issue_message: |
             Thanks for opening this issue.
 
             Before maintainers triage it, please confirm:
@@ -50,7 +50,7 @@ jobs:
             - Sensitive values are redacted
 
             This helps us keep issue throughput high and response latency low.
-          pr-message: |
+          pr_message: |
             Thanks for contributing to ZeroClaw.
 
             For faster review, please ensure: