docs: add V2EX channel to README and CHANGELOG

[kadaliao]

Summary

• Add V2EX row to the 支持的平台 table in README.md (中文)
• Add V2EX row to the Supported Platforms table in docs/README_en.md (English)
• Add [1.3.0] entry to CHANGELOG.md documenting the V2EX channel

Context

The V2EX channel was merged in #145 (feat(channels): add V2EX support via public API) but the homepage README tables were not updated at that time. This PR catches up the docs.

V2EX is a zero-config channel — public JSON API, no auth, no proxy, no API key required.

No version bump needed

pyproject.toml is already at 1.3.0 which includes the V2EX feature. This is a docs-only fix.

[Jah-yee]

I created a PR that addresses this issue!

Changes made:

• Added V2EX row to the 支持的平台 table in README.md (Chinese)
• Added V2EX row to the Supported Platforms table in docs/README_en.md (English)
• Added [1.3.0] entry to CHANGELOG.md documenting the V2EX channel

Fork with changes: https://github.com/Jah-yee/Agent-Reach/tree/docs/add-v2ex-to-readme

Since I don't have push access to the original repo, I cannot create a cross-repo PR directly. You can either:

1. Merge from my fork: https://github.com/Jah-yee/Agent-Reach/pull/new/docs/add-v2ex-to-readme
2. Or manually apply the changes from the diff below:

[Panniantong]

Thanks @kadaliao! I'll update the README and CHANGELOG myself when I cut the next release. Appreciate the follow-up from your V2EX PR though 👍