fix: keep NovaHUD headline FPS readable

[papi-ux]

Summary

• keep the complete three-digit headline FPS readable in the 236dp DEBUG NovaHUD
• constrain the lower-priority stream metadata column to 96dp so it yields width before the FPS lane
• add an RP6 Compose regression test using TextLayoutResult to require every FPS character visible with no ellipsis

Verification

• TDD RED reproduced the defect: expected 3 visible FPS characters, got 1
• NovaHudPerformanceLayoutComposeTest: 2/2 passed on physical Retroid Pocket 6
• NovaComposeSourceGuardTest: 59/59 passed
• assembleNonRoot_gameDebug passed for ARM64
• lintNonRoot_gameDebug completed successfully against the project baseline
• physical RP6 live-stream proof: DEBUG showed 114 TGT 120; Minimal showed 118; Performance showed 120/120
• Polaris returned to idle with zero test-session residuals
• independent Codex and delegated reviews found no correctness or security issues

Scope

This PR does not deploy or release Nova. The APK still identifies as version 1.3.0 / code 32; release gating remains separate.