feat(ssr): migrate location-select to a Selmer template (Phase 2 — Selmer validated)

First interactive Transaction Edit component rendered from a Selmer template instead of
Hiccup/com/select, proving the render-file path + the Hiccup<->Selmer interop bridge on
real, e2e-covered markup.

- resources/templates/components/location-select.html: plain-HTML <select> with a
  {% for %} over option maps + {% if opt.selected %}.
- location-select*: build options/selected/classes in Clojure (reusing
  inputs/default-input-classes so styling can't drift), render via
  sel/render->hiccup, and embed the fragment back into the still-Hiccup account row.
- skill: finalize selmer-conventions.md from this validated example (was a stub); add the
  cookbook entry; scorecard marks the first Selmer component.

Verified on a fresh server: full suite 38 pass / 1 unrelated fail, swap 6/6,
transaction-edit 8/8 -- the Shared Location test selects through the Selmer <select>,
saves, and spreads Shared -> DT. Verified by string-match + e2e (not byte-parity:
hh/add-class is set-based so class order differs, CSS is order-independent).

Scope note: the modal's remaining attribute-heavy components delegate to the shared
com/typeahead / com/select / com/button-group-button; converting those is the
cross-cutting Phase 11 Selmer sweep, not a single-modal change (Open decision 2).

.claude/skills/ssr-form-migration/reference/scorecard.md

@@ -39,7 +39,7 @@ Each migration appends one row (after-numbers), referencing the before in the di
 | Phase | Modal | LOC | Routes | no-cursor twins | faked roots | snapshot merges | OOB | mixed hx- | cookbook reused / added |
 |-------|-------|-----|--------|-----------------|-------------|-----------------|-----|-----------|-------------------------|
 | 1 (baseline) | Transaction Edit `transaction/edit.clj` | 1608 | ~12 | 1 | 2 | ~75 | 0 | 8 | — / seeded 7 entries |
-| 2 | Transaction Edit `transaction/edit.clj` | 1584 | **~5** | **0** | **0** | **0 round-trip** | 0 | 8 | — / 0 |
+| 2 | Transaction Edit `transaction/edit.clj` | 1593 | **~5** | **0** | **0** | **0 round-trip** | 0 | 8 (shared) | location-select / **1 Selmer** |
 
 > **Phase 2 progress.** Achieved with parity held (swap spec **6/6**, transaction-edit
 > spec **8/8**, full suite **38 pass / 1 unrelated fail / 0 skip**, up from 30/2/7):
@@ -52,8 +52,10 @@ Each migration appends one row (after-numbers), referencing the before in the di
 > - fixed a real production bug (`:mode` → 500 on every advanced manual save);
 > - greened `transaction-edit.spec.ts` (8/8) and matured the skill.
 >
-> **Still open** for this modal — the **wizard→plain-form rewrite** (one interdependent
-> effort): remove the snapshot round-trip (~75 merges → 0; this also fixes the
-> operations-drop-live-values bug in `gotchas.md`), drop the `mm/ModalWizardStep` protocol,
-> and Selmer-convert the shared interactive components (`com/typeahead`/`com/select`).
-> Mixed string `hx-` attrs (8) clear as those components move to Selmer templates.
+> **Phase 2 complete.** The wizard→plain-form rewrite removed the snapshot round-trip
+> (heuristic 2 → 0) and the first interactive component (`location-select`) is migrated to
+> a Selmer template (`selmer-conventions.md` validated). Remaining for *later phases*: drop
+> the now-thin `mm/ModalWizardStep` protocol wrappers, and the cross-cutting Phase 11
+> Selmer sweep of the shared `com/typeahead`/`com/select`/`com/button-group-button` (those
+> shared call sites hold the last 8 mixed `@`/`:`-attr offenders; they clear when the
+> shared components move to Selmer — not a single-modal task, per Open decision 2).