cache: Cache API primary + OPFS fallback, add storage diagnostics

switch model cache from Cache API to OPFS; request persistent storage

switch model cache to Cache API

add SEIS 2025 usage/impact sample

configurable span threshold + confidence chip

remove re-download button

default REAL WORLD samples, add EXAMPLES label

clarify two-model pipeline list

privacy copy: never leaves your browser

correct privacy copy

add theme toggle, intro section, and cat emoji

deploy data-use extraction webgpu demo

initial commit