SEV-329: @switchev/web-shared package — formatters, markdown, waitForImage

Stands up the shared browser-helpers package (consumed by public/vendor/admin
via the Gitea npm registry) to de-duplicate copy-pasted frontend code:
- format.js: formatLabel/formatStatus/formatTimeline/formatBudget (single source
  of truth — these had drifted, see SEV-310).
- markdown.js: renderMarkdown (marked + strict DOMPurify; both peer deps).
- wait-image.js: waitForImage (was byte-identical in public + vendor).

ESM source package (no build step — Vite consumers import directly). publishConfig
points at the Gitea npm registry. node --test green (formatters).

Next: publish v0.1.0, then migrate each site to consume it and delete the copies.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/format.test.js

@@ -0,0 +1,26 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { formatLabel, formatStatus, formatTimeline, formatBudget } from './format.js';
+
+test('formatLabel replaces _ and - and title-cases', () => {
+  assert.equal(formatLabel('contract_pending'), 'Contract Pending');
+  assert.equal(formatLabel('in-progress'), 'In Progress');
+  assert.equal(formatLabel(''), '');
+  assert.equal(formatLabel(null), '');
+});
+
+test('formatStatus is formatLabel', () => {
+  assert.equal(formatStatus('matched'), 'Matched');
+});
+
+test('formatTimeline maps known slugs, falls back otherwise', () => {
+  assert.equal(formatTimeline('6_to_12_months'), '6–12 months');
+  assert.equal(formatTimeline('flexible'), 'Flexible');
+  assert.equal(formatTimeline('something_else'), 'Something Else');
+});
+
+test('formatBudget maps known ranges', () => {
+  assert.equal(formatBudget('25k-50k'), '$25,000 – $50,000');
+  assert.equal(formatBudget('100k-plus'), '$100,000+');
+  assert.equal(formatBudget(''), '');
+});