Saved calculations in Firestore

[paccloud]

What to build

A person can save a saved calculation from the calculator and see, reopen and delete it on My data. Saved calculations are stored in Firestore under the same owner-only rules as custom yields (ADR 0001 in #122). They are private: publishing saved calculations publicly is a dropped concept.

Acceptance criteria

• "Save" in the calculator stores the calculation in Firestore for the signed-in person
• My data lists saved calculations; one can be reopened in the calculator and deleted
• Security rules allow only the owner to read and write them, with rules tests
• Saving works offline and syncs later through the persistent offline cache
• There is no publish or share option for saved calculations

Blocked by

• Custom yields in Firestore: Google sign-in and My data (tracer) #123