feat: add OpenRouter provider plugin

[robinebers]

Closes #155

Summary

• add an OpenRouter provider plugin that reads OPENROUTER_API_KEY and whitelists it in the plugin host
• show a simplified OpenRouter view with Credits, This Month, and All Time, using /credits when available and /key as fallback
• add provider docs, tests, README support listing, and the OpenRouter logo/brand color

Test plan

• bunx vitest run plugins/openrouter/plugin.test.js
• Live-checked OpenRouter /key, /credits, and /activity behavior to shape the plugin output

Made with Cursor

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Summary by cubic

Add an OpenRouter provider plugin to show account credits and spend (this month and all time). Reads OPENROUTER_API_KEY, uses /api/v1/credits when available with /api/v1/key fallback, and updates the host whitelist.

• New Features

  • Added openrouter provider plugin.
  • Displays Credits, This Month, All Time with automatic endpoint fallback.
  • Added docs (docs/providers/openrouter.md), README entry, icon, and brand color.
  • Added tests for happy path, fallback, and error cases.
  • Whitelisted OPENROUTER_API_KEY in the plugin host.

• Migration

  • Set OPENROUTER_API_KEY in your shell profile.
  • Restart the app and enable the OpenRouter plugin in settings.

^{Written for commit 57af9ec. Summary will update on new commits.}