Step 4 of the file-split refactor series. Targets backend/src/cyclone/store.py
(2,412 lines) which sits on the hot path of parse-999, parse-277ca,
reconciliation, and inbox match/unmatch.
Decisions locked:
- Public surface: cyclone/store/ subpackage + thin facade (__init__.py
re-exports every currently-importable name).
- Class shape: module functions for bodies, CycloneStore keeps its current
method signatures as 1-line delegations.
- Helper distribution: dedicated utility modules (records, orm_builders,
ui, exceptions).
13 target modules total; largest is write.py at ~210 lines. Zero public API
changes, zero test changes. Single atomic commit migration; rollback is a
single git revert.
Tyler