Add attachment upload from URL tool

[ruibaby]

Summary

• add halo_upload_attachment_from_url for transferring remote files into the Halo attachment library
• use the Console attachment policy and group without exposing storage configuration to MCP callers
• accept an optional safe filename and return the resolved attachment permalink

Security

• only accept absolute HTTP and HTTPS URLs
• delegate SSRF protection, response-size limits, timeouts, and redirect handling to Halo's AttachmentService.uploadFromUrl

Testing

• ./gradlew test --tests run.halo.mcpserver.tools.AttachmentToolsTest --tests run.halo.mcpserver.tools.BuiltInToolsTest --no-daemon
• ./gradlew check --no-daemon
• git diff --check

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-01T11:06:46.349969Z	98d0f16	PR opened

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