Add more tests for LCP client fallback and error handling

[amirHdev]

The LCP HTTP client has basic coverage now, but there are still some fallback and error paths worth pinning down.

I’m looking for small, targeted tests here, not a rewrite.

Things worth covering:

• GetLicense fallback behavior when one fetch path fails
• revoke behavior for non-200 responses beyond the already-covered soft cases
• malformed or unexpected response handling where it makes sense
• any other easy-to-isolate branch in the client

Suggested files:

• internal/lcp/license/license.go
• internal/lcp/license/license_client_test.go

Acceptance criteria:

• use httptest
• keep tests readable
• do not depend on external services
• go test ./... passes

Notes:
Good fit if you want to work on something integration-flavored without needing real infra.