test(api-v3): JIRA push flow ports + v2 test-corpus disposition table

Completes the architect-requested v2 test-corpus port (backlog
priorities 2 and 3).

JIRA flows (10 targeted tests; the v2 corpus is VCR/cassette- and
v2-entangled, so intent-ports rather than a shim):
- ImportForm gains push_to_jira (facade already accepted it), and the
  import route now ORs it with the resolved JIRA project's
  push_all_issues - mirroring v2's import/reimport viewsets; the batch
  importer path does not apply that OR itself (real gap found by the
  port). Driver resolution per mode: test -> engagement -> product.
- covered: push-per-finding on import, no-push default, push_all
  forcing (import + PATCH/PUT writes), reimport push semantics,
  import push-failure logs-and-continues (200, mirrors v2) vs finding
  writes surfacing 400 - divergence documented
- skipped with reasons: finding groups, epics, webhooks, bulk edit,
  cassette-dependent status transitions

Corpus disposition (plan \$9.1): every remaining test_apiv2_* and
API-adjacent suite classified PORTED / PORT-LATER / SKIP / SUPERSEDED;
backlog reduced to two PORT-LATER checkboxes (test dedupe-policy read
fields, authorized_users member management).

469 tests green + 6 skipped.

Author: valentijnscholten