fix(vault): prove the rebuild really deployed, and report what it moved

[pyramation]

Summary

"Rebuild database" gave no evidence it did anything, so a skipped deploy would have been indistinguishable from a working one. Two changes, both about making the operation verifiable.

It cannot silently deploy nothing. deployFresh now checks the schema it just deployed before anything is copied into it:

handle.unregister();
await Vault.assertDeployed(handle.db);   // throws unless dcrypt_vault has every COPY_ORDER table

For the record on the original worry — pgpm skipping because of its ledger — that can't happen here: registerPglite() hands back a brand-new in-memory PGlite with no pgpm_migrate schema at all (fast: true keeps no ledger), so every rebuild is a first deploy. Verified directly: the log lines a rebuild emits are identical to first-run creation (Deploying local module: pgpm-verify / pgpm-base32 / pgpm-totp / dcrypt-vault), the rebuilt database has 9 dcrypt_vault tables and no pgpm* schema, and the copied ciphertext still decrypts under the same passphrase. The assert is there so a future pgpm that does decide to skip fails loudly instead of leaving an empty database.

It says what it moved. rebuild() returns the counts instead of void:

interface RebuildReport { tables: number; copied: Record<string, number> }

so Settings reports Database rebuilt: 9 tables deployed, 34 rows carried over (12 items). rather than a flat "Every item was carried over."

copyTable returns its row count to feed that; no change to what it copies or to the on-disk format.

Testing

packages/vault: 8 tests pass, including the rebuild test (which now also exercises assertDeployed, since a rebuild that deployed nothing would throw before copying). Desktop lint, 27 tests and build pass.

Link to Devin session: https://app.devin.ai/sessions/04636534e07048089ffb6b78142e12cd
Requested by: @pyramation

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