Trim defensive positioning from docs and drop footer source link
Remove the bold "not something else" framing and sales-style copy from
README, NOTICE, and DECISIONS: the no-database/no-backend tails, the
"Why it's interesting" heading, the not-a-clone paragraph, the
wordle-fr / Le Mot comparisons, the skypress.blog mentions, the
no-git-remote handoff note, and the redundant 0-vulnerabilities aside.
Also remove the tangled.org source link (and its inlined mark) from the
app footer, along with the now-unused sourceCode i18n strings, and
update the footer tests accordingly.