add Claude Opus 4.6 (1M context) to GitHub Copilot provider

[anson627]

Issue for this PR

Closes #5993

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Adds the "Claude Opus 4.6 (1M context)" model entry to the GitHub Copilot provider's bundled models snapshot. This model is available in VS Code's GitHub Copilot model picker but was missing from OpenCode because the models.dev registry only defined a single claude-opus-4.6 entry with 144K context. The patched snapshot includes claude-opus-4.6-1m-context with a 1M token context window and 128K output limit.

Upstream fix: anomalyco/models.dev#1293 (pending merge)

How did you verify your code works?

1. Schema validation: Ran bun validate against all provider/model TOML configs in models.dev — all passed
2. API JSON verification: Built the models.dev web package (bun run build) and confirmed claude-opus-4.6-1m-context appears in the generated _api.json under the github-copilot provider
3. OpenCode model listing: Ran OPENCODE_MODELS_PATH="dist/_api.json" bun run --cwd packages/opencode --conditions=browser src/index.ts models and confirmed github-copilot/claude-opus-4.6-1m-context appears in the output alongside the existing github-copilot/claude-opus-4.6

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Hey! Your PR title add Claude Opus 4.6 (1M context) to GitHub Copilot provider doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

This PR doesn't fully meet our contributing guidelines and PR template.

What needs to be fixed:

• Not all checklist items are checked. Please confirm you have tested locally and have not included unrelated changes.

Please edit this PR description to address the above within 2 hours, or it will be automatically closed.

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

I found a potential duplicate:

PR #12342: feat(provider): add adaptive thinking and 1M context support for Claude Opus 4.6
#12342

This PR appears to be closely related to the current PR #19842 as it also adds Claude Opus 4.6 support with 1M context. Both are feature additions for Claude Opus 4.6 model support, though this one also mentions adaptive thinking support. You may want to check if these are addressing the same issue or if one supersedes the other.

[github-actions]

This pull request has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

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