docs: align Copilot cost management with AIC and model/billing docs

[Copilot]

Copilot cost guidance in the AIC documentation lacked direct references to authoritative model and billing sources and still referenced Effective Tokens where Copilot AIC is available. This update adds explicit links and aligns Copilot guidance to AIC-based cost tracking.

• AIC provider table updates

  • Updated the copilot row in docs/src/content/docs/reference/cost-management.md to include links to:
    • models.dev
    • GitHub Copilot models
    • Copilot billing
  • Clarified wording to align Copilot pricing guidance with GitHub Copilot model and billing documentation.

• Inference cost matrix updates

  • Updated the copilot engine entry in the “Inference Costs” table with the same references for consistent guidance across the page.
  • Replaced the Copilot cost metric wording from Effective Tokens/AIC unavailable to AIC-based guidance.

• Episode usage guidance updates

  • Updated Copilot-related usage guidance and example query text to use AIC terminology for Copilot cost analysis.

| `copilot` | ... | AIC (based on GitHub Copilot model and billing documentation — see [models.dev](https://models.dev/), [GitHub Copilot models](https://docs.github.com/en/copilot/concepts/about-github-copilot-models), and [Copilot billing](https://docs.github.com/en/copilot/about-github-copilot/subscription-plans-for-github-copilot)) |

[pelikhan]

@copilot copilot pricing based on github copilot models pricing and billing document

[Copilot]

@copilot copilot pricing based on github copilot models pricing and billing document

Updated in 294eb4f. The Copilot rows now explicitly state pricing is based on GitHub Copilot model and billing documentation, with links retained to models.dev, Copilot models, and Copilot billing.

[pelikhan]

@copilot AIC are available for copilot . Remove effective tokens mention

[Copilot]

@copilot AIC are available for copilot . Remove effective tokens mention

Updated in 2e6e0cd. Copilot guidance now uses AIC and removes Effective Tokens mentions in the Copilot cost rows and related Copilot usage guidance.