add fetch_url tool to CMSCompOpsAgent

[harz05]

Summary

Closes #451.

As noted by @lucalavezzo in #451, @hassan11196 already implemented an HTTP GET tool as part of the larger sandboxing feature in #433. This PR extracts just the fetch_url tool from that work and merges it independently, so the agent can fetch live URLs without needing the full Docker sandbox infrastructure.

The implementation is adapted from the http_get.py introduced in #433, refactored to match the existing tool factory pattern (create_fetch_url_tool) and wired into CMSCompOpsAgent cleanly.

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Changes

File	Description
src/archi/pipelines/agents/tools/fetch_url.py	New file: create_fetch_url_tool() factory
src/archi/pipelines/agents/tools/__init__.py	Export create_fetch_url_tool
src/archi/pipelines/agents/cms_comp_ops_agent.py	Register fetch_url in _tool_definitions() + _build_fetch_url_tool() builder
examples/agents/cms-comp-ops.md	Add fetch_url to the agent spec tools list

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How it works

• Factory function create_fetch_url_tool() follows the same pattern as other tools in the codebase (create_retriever_tool, create_file_search_tool, etc.)
• Makes an HTTP GET request using requests (already a project dependency, no new deps)
• Only http:// and https:// schemes accepted
• Credentials are stripped from URLs in logs and error messages
• Response truncated at max_response_chars (default 40 000) to avoid context window overflow
• RBAC permission tools:http_get enforced via @require_tool_permission (set required_permission=None to disable)
• Returns descriptive error strings on failure (timeouts, 4xx/5xx, connection errors) so the agent handles them gracefully without raising
• store_tool_input callback supported for tracing

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Usage

Enable via agent spec:

tools:
  - fetch_url