feat(panel): say the in-memory cache default CHANGED to off, and that the SSD pool spans cache architectures

The top-of-settings notice now states the default flipped rather than
describing the state neutrally -- an updated user needs to know something
changed under them, not just what the current setting is.

Adds blockCacheArchitecturePoolNote: the budget is one pool across plain KV
blocks, typed companion state (SSM/GatedDelta), native composite records
(DeepSeek-V4 DSA/CSA/HCA), rotating sliding-window state and multimodal
blocks -- for every model and every session. Someone reading only the
per-session note would reasonably assume a DSV4 session had its own budget.

Both in en/es/ja/ko/zh.

Also adds docs/internal/SHIP-GATES-CACHE-DEFAULTS.md: one gate per item Eric
listed, each GREEN only with a named artefact (log line, measured number,
screenshot, test file). Records what is proven, what is partly proven with the
gap named, and what is not proven -- including audio and video, which no
harness in this campaign touches, and the fact that MiniMax-M3 has 0% prefix
reuse BY DESIGN so "no reuse" must not be read as a defect for it.