SPEC v0.1 and project rules for Kvitt

Write SPEC.md v0.1 from the owner interview (requirements, data model,
stack, API outline, security, business rules, deployment, milestones,
UX sprint brief, contracts). Fill the CLAUDE.md blanks, move the Gradle
pin files into android/, point the tools at android/ and server/, and
record the git bootstrap exception in the handoff.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/decisions.md

@@ -5,4 +5,3 @@ entry and the old one a strike-through plus a pointer. The spec is updated in th
 
 | # | Date | Decision | Why | Where it lives |
 |---|---|---|---|---|
-| D-001 | YYYY-MM-DD | … | … | SPEC §… |