feat(cli): add websocket auth message configuration support

[fern-support]

Description

Link to Devin run: https://app.devin.ai/sessions/50ce682058004d24beb034e75ffe07d7
Requested by: @fern-support

Adds support for automatic authentication message sending after websocket connection. This enables SDKs to handle message-level auth patterns where the OAuth token is sent as the first message after connecting (as opposed to connection-level auth via headers/query params).

Changes Made

• Add WebSocketAuthMessageConfig type to IR with messageId and tokenPropertyPath fields
• Add auth-message field to WebSocketChannelSchema in Fern definition
• Add x-fern-auth-message extension for AsyncAPI specs
• Update AsyncAPI converters (2.x and 3.0) to extract auth message config
• Update IR migration v63-to-v62 for backward compatibility (drops the new field)
• Update Python generator to send auth message after connecting when configured
• Regenerate JSON schema files (fern.schema.json, package-yml.schema.json)
• Update CLI and Python SDK versions.yml
• Update seed/python-sdk/seed.yml irVersion to v63
• Update test snapshot for asyncapi-json-refs-ir

Human Review Checklist

• Python token retrieval: The sync version extracts token from headers via string manipulation (get_headers().get("Authorization", "").replace("Bearer ", "")). The async version uses _async_token(). Verify these approaches are robust.
• messageId field unused: The messageId is defined in the config but the Python generator only uses tokenPropertyPath to build the nested dict. Is this intentional or should the message format include the messageId?
• No test fixture: This PR doesn't include a seed test fixture to verify the generated code. Consider whether one should be added.
• Backward compatibility workaround: Uses getattr(websocket, "auth_message", None) in Python generator for compatibility with older IR types packages.

Updates Since Last Revision

• Fixed CI validation failure by updating seed/python-sdk/seed.yml irVersion from v62 to v63
• Regenerated JSON schema files that were out of sync with Fern definition changes
• Updated test snapshot for asyncapi-json-refs-ir to include new authMessage field

CI Status

Some CI checks are failing with what appear to be unrelated issues:

• valid-navigation > simple test timing out (5000ms timeout in fern-definition-validator)
• Migration test failure in v23-to-v22

These failures don't appear to be related to the websocket auth message changes.

Testing

• Lint checks pass (pnpm run check)
• Python pre-commit hooks pass
• JSON schema regeneration completed
• Test snapshots updated
• No seed test fixture added for this feature

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