CI flake: Unity WebGL build

[clockwork-labs-bot]

Detected by CI Gremlin after a failed GitHub Actions attempt succeeded on rerun.

Tests:

• Unity WebGL build

Error:
[Licensing::Client] Error: Code 20111 while processing request (status: serial has reached the maximum number of activations.)
[Licensing::Module] License activation has failed. Aborting.

Failed job runs:

• https://github.com/clockworklabs/SpacetimeDB/actions/runs/34417860797/job/102689593128 (Unity WebGL build, attempt 1 -> 2)

Timeout detection:

• none

Context:

• none

[clockwork-labs-bot]

Diagnosis for the exact linked job/attempt: run 34417860797, job 102689593128, Unity WebGL build, attempt 1.

This was PR #5888 (jdetter-patch-1) at head 982cc3d41ed233e7901f724ca22eb21b8a7a7481, checked out as merge ref 0a8feb8d03dbbf96237c291ae3fe0fac72e6c8fe, on runner ghr-github-self-hosted-ubuntu-14900k-01-spacetimedb-14-8dd30f49.

Checkout, cache restore, .NET setup, Rust setup, and Unity package build completed. The failure happened inside game-ci/unity-builder@v4 before the WebGL build proper. Unity 2022.3.32f1 repeatedly logged in, connected to the LicensingClient, and then failed license activation with:

[Licensing::Client] Error: Code 20111 while processing request (status: serial has reached the maximum number of activations.)
[Licensing::Module] License activation has failed. Aborting.
Activation failed after 5 retries
There was an error while trying to activate the Unity license.

Root cause for this exact attempt: Unity license-seat/serial activation exhaustion on the CI runner. This is CI infrastructure/licensing state, not a SpacetimeDB WebGL build failure.

Suggested updated title: CI flake: Unity WebGL build license activation hit serial maximum activations

Duplicate analysis:

• Similar same-run ticket: CI flake: unity-testsuite #5914 hit the same Unity Code 20111 serial maximum-activations failure in unity-testsuite.
• Related older Unity licensing tickets include CI flake: unity-testsuite Unity headless license not active #5581, CI flake: unity-testsuite #5838, and CI flake: unity-testsuite #5874, but those are License is not active (com.unity.editor.headless) / entitlement failures rather than the serial maximum-activations mechanism from this job.

Top duplicate candidate: no older close-enough duplicate found. Similar Unity licensing tickets exist, but none are close enough to mark this as a duplicate automatically.