refactor(ssr): Phase 3 — full Selmer migration of Transaction Bulk Code; remove the wizard

Migrates the Transaction Bulk Code modal (a single-step form wearing a full
wizard costume) to a plain Selmer form, cold-applying the ssr-form-migration
skill. Almost entirely reuse of the Phase-2 work: the whole `sc/*` Selmer
component library, `account-typeahead*` / `location-select*`, and the
`edit-modal` / `transitioner` chrome are imported wholesale.

What changed
- Wizard removed: deleted `BulkCodeWizard` / `AccountsStep` records,
  `MultiStepFormState`, the `step-params[...]` prefix, and all `mm/*`
  middleware. Replaced with a plain handler + flat `wrap-bulk-state` (decode
  straight into `bulk-code-schema`, no snapshot round-trip).
- Selection round-trip: the non-editable transaction selection is resolved to
  a concrete not-locked id vector at open and ridden back in hidden `ids[]`
  fields (the bulk analog of edit's single `db/id`) — no EDN snapshot, no
  filter re-query, and more correct (codes exactly the rows the user saw).
- 100% Selmer render path (only the shared terminal `com/success-modal` keeps
  Hiccup — heuristic-9 exception). New shared component `sc/select`
  (`location-select.html` generalized) for the status dropdown.
- Routes 4 -> 3: GET `bulk-code` (open), POST `bulk-code-submit`, POST
  `bulk-code-form-changed` (one whole-form op dispatcher folding the old
  `new-account` + `vendor-changed` routes). Location swap moved off `find *`
  onto explicit `#account-location-<index>` + `hx-select`.
- Fixed a latent correctness bug surfaced by the migration: the vendor
  typeahead needs `:id` (value-keyed `:key`) or its value-bound hidden goes
  stale across a whole-form swap and posts blank.

Scorecard delta (transaction/bulk_code.clj): mm coupling 19->0, snapshot
merges 4->0, wizard records 3->0, step-params 10->0, routes 4->3, OOB 0,
Hiccup-in-render ->0 (bar success-modal). LOC 420->506 (documented exception:
the wizard was a thin shell over mm/* defaults, so explicitness moves shared
plumbing into the file). Cookbook: reused the entire Phase-2 sc/* lib + chrome,
added sc/select.

Verification: bulk-code-transactions.spec.ts 13/13; full Playwright suite
39/39; cljfmt clean.

Skill fed: scorecard row + narrative + LOC exception; gotchas (value-bound
typeahead keying, selection-as-ids round-trip); cookbook (sc/select).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

resources/templates/transaction-bulk-code/bulk-code-form.html

@@ -0,0 +1,5 @@
+{# Top-level plain form for bulk-code (no wizard). The resolved (not-locked) transaction
+   id set rides in hidden ids[] fields -- the analog of the edit modal's single db/id
+   hidden -- so the selection survives form-changed / submit posts without an EDN snapshot
+   or a filter round-trip. #}
+<form id="bulk-code-form"{{ form_attrs|safe }}>{{ ids_hidden|safe }}{{ modal|safe }}</form>