Add Operator CRD Types for Auth Server Redis Storage

[tgrunnagle]

Closes #3792

Summary

Adds Kubernetes CRD types for configuring Redis storage in the embedded authorization server. This defines the declarative schema that operators will use to configure Redis-backed storage for horizontal scaling, building on the core Redis storage backend (#3628) and integration tests (#3629). The controller and runner integration that consumes these types is tracked separately in #3630.

Changes Made

CRD Types (mcpexternalauthconfig_types.go)

• Added AuthServerStorageConfig with type field supporting memory (default) and redis backends
• Added RedisStorageConfig with Sentinel configuration, ACL user authentication, and configurable timeouts (dial, read, write)
• Added RedisSentinelConfig with masterName, sentinelAddrs (explicit addresses), and sentinelService (Kubernetes Service discovery) — mutually exclusive
• Added SentinelServiceRef for referencing a Kubernetes Service for Sentinel discovery (name, namespace, port)
• Added RedisACLUserConfig with SecretKeyRef references for username and password
• Added Storage field to EmbeddedAuthServerConfig

Validation Webhooks (mcpexternalauthconfig_webhook.go)

• Added validateStorageConfig enforcing type-specific configuration presence
• Added validateRedisStorageConfig requiring sentinelConfig and aclUserConfig, plus Go duration format validation for timeout fields
• Added validateRedisSentinelConfig enforcing exactly one of sentinelAddrs or sentinelService
• Added validateRedisACLUserConfig requiring both secret references
• Integrated storage validation into existing validateEmbeddedAuthServer flow

Generated Files

• Updated zz_generated.deepcopy.go with DeepCopy methods for all new types
• Updated CRD manifests in deploy/charts/operator-crds/ (both files/ and templates/)

Implementation Details

• Simplified the issue's proposed design by removing deploymentMode and authType enum fields — since only sentinel and aclUser are supported, these are implicit in the type structure rather than configurable enums
• Follows existing patterns: SecretKeyRef for secret references, kubebuilder validation annotations for enums and defaults, optional fields with sensible defaults

Testing

• Added TestMCPExternalAuthConfig_ValidateStorageConfig with 17 test cases covering:
  • Default/explicit memory storage, invalid memory+redis combinations
  • Valid Redis with sentinel addrs and sentinel service ref
  • Missing required fields (sentinel config, master name, ACL config, secret refs)
  • Mutual exclusivity of sentinelAddrs vs sentinelService (both set, neither set)
  • Empty sentinel service name
  • Valid and invalid Go duration timeout strings (dial, read, write)
• All tests are parallel and use table-driven patterns consistent with existing tests

Additional Notes

• Blocks Auth Server: Operator Controller & Runner Integration for Redis Storage #3630 (Controller & Runner Integration) which will consume these types
• Related: Auth Server: Add Redis Storage Documentation (Phase 3) #3790 (Documentation)

Large PR Justification

• Isolated CRD updates and corresponding webhooks/tests only

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[codecov]

Codecov Report

❌ Patch coverage is 96.15385% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.76%. Comparing base (c8f2254) to head (b3c4bb3).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ator/api/v1alpha1/mcpexternalauthconfig_webhook.go	96.15%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3793      +/-   ##
==========================================
- Coverage   66.78%   66.76%   -0.02%     
==========================================
  Files         437      437              
  Lines       43002    43057      +55     
==========================================
+ Hits        28718    28748      +30     
- Misses      12078    12105      +27     
+ Partials     2206     2204       -2     

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[jhrozek]

nit: constants would be nicer

[jhrozek]

just a note, we should probably mention this in the docs, along with howto (just the thv part of it) on setting up the redis storage