* fix: MCP tool calls fail when MCP_AUTH_TOKEN and TENANT_API_KEY differ
When both HINDSIGHT_API_MCP_AUTH_TOKEN and ApiKeyTenantExtension are
configured with different values, MCP transport auth passes but tool
execution fails because the MCP token gets re-validated against the
tenant API key in the engine layer.
Add mcp_authenticated flag to RequestContext so the engine skips tenant
re-validation when MCP transport auth already succeeded.
Fixes#627
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* test: strengthen assertion to verify no auth error in tool response
The original test only checked that "banks" key existed in the response,
which was true even for error responses like {"error": "...", "banks": []}.
Now asserts "error" not in parsed to properly catch auth failures.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>