Move writeComposerPaste out of electron/main.ts into composer-paste.ts
(placement gate: no new behaviour appended to the facade). Lower the
conversion threshold from 10k to 3k characters so a pasted stack trace or
log excerpt already becomes a chip. Trim the policy tests to two
invariants (strict threshold boundary; chip size label is byte-based) and
drop vendor references from code comments.
Teknium