Fix double-encoded UTF-8 mojibake across source files (#10)

A prior tool re-saved these files reading their UTF-8 bytes as CP1252 and
writing them back as UTF-8, double-encoding every non-ASCII glyph. Visible
fallout included garbled separators next to column headers on /add-nodes
(middot rendered as "A-circ middot") and corrupted em-dashes/box-drawing in
section headers and user-facing strings.

Reversed the double-encoding (cp1252 -> utf-8 round-trip) on maximal runs of
affected characters only; ASCII and already-correct Unicode untouched. Real
glyphs restored: em-dash, middot, ellipsis, box-drawing.

  public/index.html  655 runs fixed
  server.js          216 runs fixed
  cli.js              68 runs fixed
  lib/errors.js       15 runs fixed

Syntax-verified (node --check on each JS file + extracted inline script);
server restarts clean and serves mojibake-free HTML.

Co-authored-by: Sentinel-Bluebuilder <Sentinel-Bluebuilder@users.noreply.github.com>

Author: Sentinel-Bluebuilder