fix: skip token exchange when no credentials configured (OSS Conductor auth)

[manan164]

Problem

When OrkesAuthenticationSettings is not configured (null KeyId/KeySecret), accessing Configuration.AccessToken calls TokenHandler.GetToken() which unconditionally proceeds to POST /api/token. On OSS Conductor this endpoint returns 404/405, causing an unhandled exception and preventing the SDK from being used against unauthenticated OSS deployments at all.

Fix

Added early-return guards in both GetToken() and RefreshToken() in TokenHandler.cs: if authenticationSettings is null or either KeyId/KeySecret is null or empty, return null immediately without attempting the token exchange.

This is safe because:

• If auth is not configured, the caller should not expect a token.
• The existing Configuration.AccessToken property already returns null when AuthenticationSettings is null, so downstream code already handles null tokens.
• Authenticated (Orkes Cloud) deployments are unaffected — they always provide non-empty credentials.

Changes

Conductor/Client/Authentication/TokenHandler.cs

• GetToken(): return null early when credentials are absent
• RefreshToken(): return null early when credentials are absent

Testing

To reproduce the bug before this fix: create a Configuration with no AuthenticationSettings, call any API method, observe the 404/405 exception from TokenHandler. After this fix the call proceeds without a token (appropriate for OSS Conductor).

[codecov]

Codecov Report

❌ Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
Conductor/Client/Authentication/TokenHandler.cs	0.00%	10 Missing ⚠️

Flag	Coverage Δ
unittests	1.05% <0.00%> (-0.01%)	⬇️

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Files with missing lines	Coverage Δ
Conductor/Client/Authentication/TokenHandler.cs	12.72% <0.00%> (-2.83%)	⬇️

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[manan164]

Closing — the Agentspan SDK sets AuthenticationSettings = null for OSS Conductor, which is already handled correctly in 1.1.4. This fix would only apply if someone passes OrkesAuthenticationSettings with empty credentials, which is not our use case.