fix(csv): keep the fidelity header, signed numbers and safe settings

[daggerok]

What changed

Fixes from a bug review of the viewer:

• Fidelity exports: the header row was dropped (data rows end with a comma, so the header has one field less) and an empty Col 40 appeared; now the header is kept and the empty trailing column dropped
• Parser: a bare " inside an unquoted value swallowed the rest of the file; two-column files lost their rows when a wider preamble line existed; CR-only line endings; an over-wide row no longer loses its last field
• Types: signed percent and money (+1.33%, +$89.08) were text, so they sorted alphabetically and >0 found nothing; $-2.49 was positive
• Filters: >1,000 was split into >1 OR =0; >$100 and 5% now work numerically; a lone ! hid every row; a filter on a column index the file does not have hid every row of that file
• Settings from localStorage or an imported JSON are validated field by field (null maps crashed the page at boot)
• Reset no longer wipes the remembered data; a skipped save (too large, quota) clears the old copy and alerts instead of silently restoring stale data; clearing a renamed column restores the header name
• Export All CSV Files spaces out the downloads and revokes URLs later; importing more files keeps the open file selected

Checks run

• bun run build: ok
• Functions extracted from src/main.tsx run with bun on a real Fidelity export and small inputs: 14 passed, 0 failed
• Headless Chrome on the built site (damaged settings boot, Fidelity import shows the header, no Col 40, no disclaimer rows, data survives Reset + reload): 5 passed, 0 failed; console errors: none