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.

.env.example

@@ -81,3 +81,16 @@ PROVIDER=openrouter
 #
 # Common models: glm-5, glm-4.7, glm-4-plus, glm-4-flash
 # See docs/zai-glm-setup.md for detailed configuration.
+
+# ── Web Search ────────────────────────────────────────────────
+# Web search tool for finding information on the internet.
+# Enabled by default with DuckDuckGo (free, no API key required).
+#
+# WEB_SEARCH_ENABLED=true
+# WEB_SEARCH_PROVIDER=duckduckgo
+# WEB_SEARCH_MAX_RESULTS=5
+# WEB_SEARCH_TIMEOUT_SECS=15
+#
+# Optional: Brave Search (requires API key from https://brave.com/search/api)
+# WEB_SEARCH_PROVIDER=brave
+# BRAVE_API_KEY=your-brave-search-api-key