feat: tx list --flat, account create --if-not-exists, --since/--until doc (v0.3.6)v0.3.6

Three smaller ISSUES.md items, one PATCH (two optional flags + a doc fix; no
existing caller or JSON shape changes).

- tx list --flat: emit one top-level object per split (journal id repeated),
  dropping the transactions[] nesting so single-split journals script cleanly.
  JSON-only; --human already explodes splits into a table.
- account create --if-not-exists: resolve the name first; on a clash return the
  existing account with "existed": true (exit 0) instead of surfacing Firefly's
  422, so import scripts are idempotent. Detects via resolver, not by parsing
  the error string.
- SKILL.md documents that --since/--until filter on the transaction date (the
  value date); Firefly journals have a single date field, no separate book date
  (verified against firefly-iii TimeCollection setRange).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions