Fix GameRenderer blur mixin for 1.21.1

docs/agent-handoff.md

@@ -23,6 +23,7 @@ The Gitea runner has been used for:
   - `AsyncCraterManager`
   - `BlockIndexManager`
 - Updated the `ExplosionMixin` complex constructor injection descriptor for Minecraft `1.21.1` after a client bootstrap crash showed the old Forge `1.20.1` constructor target no longer exists.
+- Updated `GameRendererBlurMixin` render callback and invoke descriptors for Minecraft `1.21.1` after the next client crash showed `GameRenderer#render` now receives `DeltaTracker, boolean`.
 - Fixed runner setup issues:
   - executable `gradlew`
   - tracked `gradle-wrapper.jar`
@@ -34,6 +35,7 @@ The Gitea runner has been used for:
 | --- | --- |
 | `git diff --check` | PASS before last committed source fixes |
 | `git diff --check` | PASS after NeoForge `21.1.225` metadata change and `ExplosionMixin` runtime crash fix |
+| `git diff --check` | PASS after `GameRendererBlurMixin` runtime crash fix |
 | Gitea decompile workflow | PASS |
 | Gitea build workflow | FAIL, now reaches Java API migration errors |
 
@@ -63,6 +65,7 @@ The remaining failures are real Forge-to-NeoForge/API-porting work, not runner s
 3. Replace GUI overlay events and config screen registration.
 4. Re-run the Gitea build after each API family rather than attempting all files at once.
 5. Retest the client jar after the `ExplosionMixin` descriptor fix; the next crash, if any, should be a later runtime/API issue rather than the bootstrap constructor mismatch.
+6. Retest the client jar after the `GameRendererBlurMixin` descriptor fix; the next crash, if any, should be the next stale mixin/API target.
 
 ## Risks