Add apiKey field to mcpServers block schema for Bearer token auth

[continue]

Description

This PR adds an apiKey field to the mcpServers block schema in packages/config-yaml and implements it as a Bearer token in the Authorization header across both the core MCP connection and the CLI MCP service.

Changes

• Schema: Added apiKey field to sseOrHttpMcpServerSchema in packages/config-yaml/src/schemas/mcp/index.ts
• Core Implementation: Updated MCPConnection.ts to merge apiKey as Authorization: Bearer <apiKey> header in both SSE and HTTP transports
• CLI Implementation: Updated MCPService.ts to merge apiKey as Authorization: Bearer <apiKey> header in both SSE and HTTP transports
• Type Definitions: Added apiKey?: string to InternalSseMcpOptions and InternalStreamableHttpMcpOptions in core/index.d.ts
• Converter: Updated yamlToContinueConfig.ts to pass through the apiKey field

Usage Example

Users can now specify an apiKey directly in their mcpServers config instead of needing to use requestOptions.headers:

mcpServers:
  - name: my-server
    url: https://api.example.com/mcp
    apiKey: sk-1234567890abcdef

This will automatically set the Authorization: Bearer sk-1234567890abcdef header.

Fixes CON-4281

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This agent session was co-authored by nate and Continue.

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Summary by cubic

Add apiKey to the mcpServers schema and automatically send it as a Bearer token in Authorization headers for SSE and streamable HTTP transports. This simplifies MCP auth configuration and fulfills CON-4281.

• New Features

  • Added apiKey to sseOrHttpMcpServerSchema.
  • Automatically sets Authorization: Bearer in core MCPConnection and CLI MCPService.
  • Updated types and yaml converter to support apiKey.

• Migration

  • Use mcpServers.apiKey to enable Bearer auth.
  • Remove duplicate Authorization headers from requestOptions if present.

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[sestinj]

🎉 This PR is included in version 1.27.0 🎉

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[sestinj]

🎉 This PR is included in version 1.24.0 🎉

The release is available on:

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• GitHub release

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[sestinj]

🎉 This PR is included in version 1.2.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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