fix: propagate identity for token exchange + add real integration tests

[yrobla]

when using the discovered mode on vmcp, we discovered that it was not working because identity was not propagated. Add a fix and add proper testing to validate

Large PR Justification

This is a complete fix of the feature, including unit tests. The fixes are atomic and need to come together to solve the issue

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[codecov]

Codecov Report

❌ Patch coverage is 54.54545% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.56%. Comparing base (00c066e) to head (373ed73).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/vmcp/client/client.go	54.54%	5 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@ ## main #2769 +/- ## ========================================== - Coverage 56.56% 56.56% -0.01%  ========================================== Files 320 320 Lines 30873 30882 +9 ========================================== + Hits 17464 17468 +4  - Misses 11908 11913 +5  Partials 1501 1501 

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[Copilot]

Pull request overview

This PR fixes token exchange for discovery mode in the Virtual MCP (vmcp) system by addressing configuration format issues and adding comprehensive end-to-end testing with mock servers deployed as Kubernetes resources.

Key Changes:

• Fixes vmcp configuration YAML format conversion to use a flat token_cache.config structure instead of separate memory/redis sections, aligning with the YAML loader's expected format
• Adds discovery logic for incoming OIDC configuration from backend MCPServers, enabling vMCP to authenticate to backends that require OIDC
• Implements comprehensive E2E tests with mock HTTP, OAuth token exchange, and OIDC servers deployed as Kubernetes pods to validate authentication flows

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
test/e2e/thv-operator/virtualmcp/virtualmcp_auth_discovery_test.go	Replaces simple httptest mock with Kubernetes-deployed mock servers (HTTP, OAuth, OIDC) for realistic E2E testing of auth discovery and token exchange flows
test/e2e/thv-operator/virtualmcp/helpers.go	Adds GetPodLogs helper function to retrieve logs from specific pods for debugging test failures
test/e2e/oidc_mock.go	Implements proper JWKS endpoint with RSA public key export and adds client_credentials grant type support
pkg/vmcp/workloads/k8s.go	Adds discoverIncomingOIDCConfig method to discover and populate OIDC configuration from backend MCPServers, enabling vMCP→backend authentication
pkg/vmcp/types.go	Adds IncomingOIDCConfig field to Backend and BackendTarget types for storing discovered OIDC configuration
pkg/vmcp/registry.go	Propagates IncomingOIDCConfig field when converting Backend to BackendTarget
cmd/thv-operator/controllers/virtualmcpserver_vmcpconfig.go	Implements convertToCLIFormat to transform Go config structs into vmcp CLI-compatible YAML format with flat token_cache.config structure

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[github-actions]

✅ Large PR justification has been provided. The size review has been dismissed and this PR can now proceed with normal review.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

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