Add a small Go + SQLite service (server/) that stores character-sheet
JSON blobs and returns short, content-addressed IDs, so sheets can be
shared via a compact ?s=<id> link instead of an oversized inline payload.
CharacterSheet.tsx now POSTs to the service on share and fetches by ID on
load, falling back to the self-contained ?c= inline link when the backend
is unreachable. Legacy ?c= links still decode.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
