Increase frozen perf compute budget by 50%

[bill-ph]

Summary

• increase the frozen-perf Duckgres worker from 2 CPU / 8Gi to 3 CPU / 12Gi
• run three Trino workers at 1 CPU / 4Gi each so aggregate execution resources remain matched
• use a 3G heap and 2GB per-node query memory, with a 6GB cluster-wide query limit
• update resource contracts and runbook documentation

Tests

• go test -count=1 ./tests/mw-dev/scenario ./tests/mw-dev ./tests/perf/publishercli
• just lint

[github-actions]

Test Impact Plan

Deterministic summary of how this PR changes tests, CI runners, and coverage-risk signals.

Summary

Area	Added	Changed	Deleted
Test files	0	5	0
E2E/journey files	0	0	0
Workflow files	0	1	0

Signals

• Test cases: +0 / -0
• Assertions: +1 / -0
• Skips or known failures added: 0
• Workflow continue-on-error added: 0
• Workflow path filters added: 0
• Test commands removed from justfile: 0
• E2E/journey retry lines added: 0

Coverage risk: neutral or increased

No coverage-reduction warnings detected.