docs: move still-open review findings into readme and drop docs folder

[daggerok]

What changed

• docs/FINDINGS.en.md and docs/FINDINGS.ru.md (same 8 findings, EN and RU) re-checked against current master
• Still-open findings condensed into a Known Issues section at the end of README.md
• docs/ removed

Verdict per finding

Finding	Status	Evidence
F-01 monolithic main.tsx	open	src/main.tsx is 1821 lines
F-02 large files	open	no Worker, no virtualization, datasets in localStorage
F-03 A quoted whitespace trimmed	open	parseCSVText trims every field
F-03 B over-wide rows cut	fixed (#19)	rows are padded, only an all-empty trailing column is dropped
F-04 rememberData default on	open	rememberData: true in DEFAULT_SETTINGS
F-05 settings shared by index	partly	pins per file since #21; names, types, filters, sort still global
F-06 README and deps drift	open	README says Vite; clsx, lucide-react, recharts, tailwind-merge, papaparse unused; bun audit 33 dev-only, --prod clean
F-07 no tests	open	test script runs the build, CI only builds
F-08 a11y and errors	open	clickable <div> empty state, alert(), console.error

How it was checked

• grep and read of src/main.tsx, package.json, .github/workflows/*
• bun audit, bun audit --prod, bun pm why js-yaml
• git diff --check