test(perf): prove cache resilience

[m1ngsama]

Summary

• add test-only component-wise accounting for every bounded mutable App allocation
• prove resize, navigation, search, suspend/resume, allocation-error, and terminal-I/O retry sequences plateau after one maximum warm round
• sample after every App action, background phase, and draw without adding production telemetry

Verification

• independent review: no blocker
• current and Rust 1.88 strict Clippy plus full 381 unit / 29 CLI-PTY / 5 documentation tests
• release tests with overflow checks
• package verification and make bounded-results: 16 ASCII NDJSON records, 8,418 bytes

Refs #12

The issue remains open until the final external PTY timing and RSS baseline is published.