fix(readme): repair UTF-8 double-encoding from the prior docs commit

The previous docs commit corrupted the README: an inline perl \x{} escape under
-0777 upgraded the whole byte-string and double-encoded every pre-existing UTF-8
char (the glyphs, the multiplication/en-dash signs). Restored the clean text and
re-applied all edits via UTF-8-byte heredocs (no \x escapes). Same content: stale
Pages/CI URL fixes, Web Interface rewrite for the Encode/Decode tabs, container in
Features, hexlike -X docs, honest Compactness/Trade-off expansion figures, plus a
new whitespace-incursion-resistance note on the Usability bullet.

Author: pmarreck