RP Card Vault 1.5.2

A tidy-up of the code changed since 1.3.0. Almost all of it works exactly as
before; two small differences:

• Two more folder settings follow your folders after an import or when a
  folder replaces the one inside it: the duplicate finder's per-folder
  choices, and the folders Ingest last used.
• Ingest's "Move source to _ingested/" uses the same checked move as the
  rest of the vault, so it shows up in the Log like any other move.

Under the hood: one copy of the "move, check, then remove" steps, one guard
against files that unpack to gigabytes, the agent chat no longer re-reads
its tool results for every piece of a streamed reply, the grid is told when
it appears instead of checking after every change, and the Python fallback
updates its copy of the vault instead of rebuilding it each start.