fix(fusion_accounting_bank_rec): MV correctness for V19 schema + Odoo test harness

Three issues surfaced when running the MV smoke tests against westin-v19:

1. account_bank_statement_line has no `date` column in V19 — `date` is a
   related field flowing through move_id -> account_move.date. The MV
   now JOINs account_move and selects am.date.
2. is_reconciled is nullable; replace `= FALSE` with `IS NOT TRUE` so
   nulls (genuinely unreconciled lines that haven't had the compute run
   yet) are still included.
3. _refresh() now flushes the ORM cache (env.flush_all()) before the
   REFRESH so computed-stored fields like is_reconciled are written to
   the DB before the materialization snapshot reads them. Previously the
   reconcile-then-refresh path saw the pre-reconcile column value.
4. _trigger_mv_refresh() (suggestion create/write hook) now uses
   concurrently=False because Postgres forbids
   REFRESH MATERIALIZED VIEW CONCURRENTLY inside a transaction block,
   and Odoo's per-request cursor is always inside one. The cron path
   (Task 25) will open an autocommit cursor for CONCURRENTLY refreshes.
5. Tests dropped the env.cr.commit() pattern: Postgres always shows a
   transaction its own writes, so a non-CONCURRENTLY refresh in the
   same txn picks up freshly-inserted rows. Cleaner + works inside
   TransactionCase, which forbids cr.commit().

Verified: 4 new MV tests pass, 0 failures across 118 logical tests
(178 with parametrized property-based runs) of fusion_accounting_bank_rec
on westin-v19.

Made-with: Cursor

fusion_accounting_bank_rec/data/sql/create_mv_unreconciled_bank_line.sql

@@ -2,12 +2,15 @@
 -- Refreshed on cron (Task 25) and on suggestion writes.
 -- Indexed on (company_id, journal_id, date) for fast UI queries.
 
+-- NOTE: account_bank_statement_line does not store `date` directly in V19;
+-- it is a related field through move_id -> account_move.date. We JOIN on
+-- account_move to get it.
 CREATE MATERIALIZED VIEW IF NOT EXISTS fusion_unreconciled_bank_line_mv AS
 SELECT
     bsl.id                                         AS id,
     bsl.company_id                                 AS company_id,
     bsl.journal_id                                 AS journal_id,
-    bsl.date                                       AS date,
+    am.date                                        AS date,
     bsl.amount                                     AS amount,
     bsl.payment_ref                                AS payment_ref,
     bsl.currency_id                                AS currency_id,
@@ -41,7 +44,8 @@ SELECT
         WHERE p.partner_id = bsl.partner_id AND p.company_id = bsl.company_id LIMIT 1), 0)
                                                                  AS partner_reconcile_count
 FROM account_bank_statement_line bsl
-WHERE bsl.is_reconciled = FALSE;
+JOIN account_move am ON am.id = bsl.move_id
+WHERE bsl.is_reconciled IS NOT TRUE;
 
 -- Indexes for the common UI queries: filter by company + journal, sort by date desc.
 CREATE INDEX IF NOT EXISTS fusion_mv_unrec_company_journal_date_idx