chore: sync fork with upstream + update .gitignore for AI agent files

[alfonsodg]

Problem 1: Fork is 7 commits behind upstream

Our fork (alfonsodg/MiniMax-MCP) is 7 commits behind MiniMax-AI/MiniMax-MCP. The upstream changes are documentation updates (mmx-cli recommendation in READMEs).

Missing upstream commits

7b4d707 Merge pull request #57 — docs: recommend mmx-cli
d13c627 docs: remove Also in English README
fdd7276 docs: minor wording fix in Chinese README
43c8f4a docs: simplify mmx-cli recommendation
226310d docs: add agent skill install command for mmx-cli
76ef6d9 Merge pull request #56 — docs: recommend mmx-cli
d40898e docs: add mmx-cli recommendation to README

Proposed fix

git fetch upstream
git merge upstream/main
# Resolve any conflicts in README.md (our CLI args docs vs their mmx-cli recommendation)
git push origin main

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Problem 2: .gitignore missing AI agent config files

AGENTS.md and .github/copilot-instructions.md are untracked but should be explicitly ignored per project standards:

$ git status --short
?? .github/copilot-instructions.md
?? AGENTS.md

Proposed addition to .gitignore

# AI agents & copilot
AGENTS.md
.github/copilot-instructions.md
.github/copilot*.md

Acceptance criteria

• Fork is up to date with upstream/main
• .gitignore excludes AI agent configuration files
• No untracked AI config files in git status