feat(plugins): add minimax-code-checkin

[RedMaple-mc2]

What

Adds a new community Plugin: MiniMax Code ��签� � wraps MiniMax
Code's built-in daily check-in (added in v3.0.58, 2026-08-05) as a
reusable Skill, and lets the user manage the cron that schedules the
automated check-in.

Why

• Users want the daily check-in automated so they don't forget and
  lose their consecutive-day streak (day 4 and day 7 reward 1000
  credits each; full week is 4000).
• There is no first-class CLI or API for the check-in today, so the
  Skill drives the existing UI workflow and delegates schedule
  changes to mavis cron.

Capability

• Skill: skills/minimax-code-checkin/SKILL.md
  • mode A â�� run the daily check-in now (cookie / OAuth login check
    � Settings � Usage � click ��签�).
  • mode B â�� query current cron schedule / next run.
  • mode C â�� change cron time, enable/disable via mavis cron update.
• No MCP servers, no App dependencies.

Requirements

• MiniMax Code >= v3.0.58 (the check-in surface exists from this
  release onward).
• A logged-in MiniMax Code session (browser cookie or desktop OAuth
  cache). First run will prompt the user to log in if neither is
  present.

Network access

None. The Skill operates against the user's already-open MiniMax
Code session and mavis cron; it does not call any external
endpoint.

Data use

• Reads existing OAuth/cookie state only to detect login.
• Does not collect, store, or transmit any user data outside the
  MiniMax Code session.
• No secrets, no telemetry, no native binaries, no symlinks.

Test plan

• node scripts/lint-skill.js skills/minimax-code-checkin passes
  (verified locally � 8/8 OK).
• node scripts/validate.mjs passes â�� OK plugin RedMaple-mc2/minimax-code-checkin
  alongside the other 28 hosted Plugins and 4 examples.
• node --test test/validation.test.mjs â�� 22/22 pass.
• node --test test/hosted-plugins.test.mjs â�� 7/7 pass.
• node --test test/validation-crlf.test.mjs â�� 4/4 pass.

Checklist

• Path is plugins/RedMaple-mc2/minimax-code-checkin/.
• plugin.json schema-version URL, name kebab-case, license declared.
• Author = RedMaple-mc2.
• LICENSE is MIT and matches the copyright header.
• No secrets, private endpoints, native binaries, or symlinks.
• Skill frontmatter name matches directory.
• Example query, requirements, network access, and data use are
  documented in README.md.

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