[codex] prune raw train rollout payloads

[samsja]

Summary

Prunes duplicate raw train rollout payloads after trainer samples are built:

• projects raw token dicts into a small allowlisted compact payload
• keeps only token lengths and routed-expert shape metadata in the raw trajectory
• drops token fields that are not needed after TrainingSample construction
• keeps trainer-bound TrainingSample payloads intact
• lets filters read generated token/logprob data from samples when raw tokens are pruned
• keeps token length penalty, turn-count metrics, and monitor logging compatible with compacted raw payloads
• keeps scalar temperature changes out of this PR

Ablation

Same fast no-inference routed-payload run used for the memory stack: 5 steps, batch=64, inflight=128, seq_len=32768, turns=50, max_off_policy=4, delay mean 0s, std 3.33s.

layer	post-step RSS totals GiB	post-step peak	external peak	runtime
trim + GC + release refs	4.378, 6.056, 7.571, 9.283, 9.741	9.741	15.838	1m33s
+ raw pruning	4.099, 5.746, 6.729, 8.377, 9.276	9.276	12.508	1m35s

Takeaway: raw pruning reduces external peak RSS by about 3.33 GiB; post-step retained RSS drops by about 0.47 GiB.

Validation

• uv run ruff check src/prime_rl/orchestrator/trajectories.py src/prime_rl/orchestrator/filters.py src/prime_rl/orchestrator/train_sink.py src/prime_rl/orchestrator/types.py src/prime_rl/orchestrator/utils.py src/prime_rl/orchestrator/metrics.py src/prime_rl/orchestrator/orchestrator.py src/prime_rl/utils/monitor/prime.py src/prime_rl/utils/monitor/wandb.py tests/unit/orchestrator/test_trajectories.py tests/unit/orchestrator/test_filters.py tests/unit/orchestrator/test_advantage.py
• uv run ruff format --check src/prime_rl/orchestrator/trajectories.py src/prime_rl/orchestrator/filters.py src/prime_rl/orchestrator/train_sink.py src/prime_rl/orchestrator/types.py src/prime_rl/orchestrator/utils.py src/prime_rl/orchestrator/metrics.py src/prime_rl/orchestrator/orchestrator.py src/prime_rl/utils/monitor/prime.py src/prime_rl/utils/monitor/wandb.py tests/unit/orchestrator/test_trajectories.py tests/unit/orchestrator/test_filters.py tests/unit/orchestrator/test_advantage.py
• uv run pytest tests/unit/orchestrator/test_trajectories.py tests/unit/orchestrator/test_filters.py tests/unit/orchestrator/test_advantage.py tests/unit/orchestrator/test_batch.py tests/unit/train/rl/test_packer.py
• git diff --check

[mikasenghaas]

wouldnt merge this imo