service editors: "To EF filter" per-service cross-link

In the SST/UST/IST/EST decoded editors, each service row backed by files
gains a small "To EF filter" action that sets the file-tree filter to
exactly that service's option:

- The four service-table fields carry a `table` key (sst/ust/est/ist);
  servicesFeatureByNumber() inverts SERVICES_CROSS_REF into per-table
  number->feature maps (lazy, cached).
- pysimFsFilterBtnHtml(table, n) renders the button only for file-backed
  features; pysimFsSetFilterToService(table, n) sets pysimFsFilter to
  ['svc:<feature>'], persists, and re-renders the dropdown + tree.
- i18n: "To EF filter" (EN/RU).  No CSS rebuild needed.

Frontend 1152 tests green (+6).  (Version/sw bump still deferred.)

frontend/tests/fs_service_link.test.js

@@ -0,0 +1,127 @@
+// The service-table rows' cross-link to the file-tree filter: a table row
+// that is backed by files gets a "To EF filter" button that narrows the tree
+// to exactly that service's files.
+const { test } = require('node:test');
+const assert = require('node:assert');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const html = fs.readFileSync(path.join(__dirname, '..', 'index.html'), 'utf8');
+
+function extractFunc(src, name) {
+	const re = new RegExp('(?:async\\s+)?function\\s+' + name + '\\s*\\([^)]*\\)\\s*\\{');
+	const m = re.exec(src);
+	if (!m) throw new Error('function ' + name + ' not found');
+	let i = m.index + m[0].length - 1;
+	let depth = 0;
+	for (; i < src.length; i++) {
+		if (src[i] === '{') depth++;
+		else if (src[i] === '}') {
+			depth--;
+			if (depth === 0) break;
+		}
+	}
+	return src.slice(m.index, i + 1);
+}
+
+function extractConst(src, name) {
+	const m = new RegExp('const ' + name + ' = ').exec(src);
+	if (!m) throw new Error('const ' + name + ' not found');
+	const begin = m.index + m[0].length;
+	const opener = src[begin];
+	const closer = opener === '[' ? ']' : (opener === '{' ? '}' : null);
+	if (!closer) throw new Error('unsupported const ' + name);
+	let depth = 0, i = begin;
+	for (; i < src.length; i++) {
+		if (src[i] === opener) depth++;
+		else if (src[i] === closer) {
+			depth--;
+			if (depth === 0) { i++; break; }
+		}
+	}
+	return 'var ' + name + ' = ' + src.slice(begin, i) + ';\n';
+}
+
+// module state the extracted functions close over
+let pysimFsFilter = new Set(['all']);
+let _servicesFeatureByNumber = null;
+const _store = {};
+let _renders = 0;
+let _treeRenders = 0;
+
+globalThis.localStorage = {
+	getItem: k => (Object.prototype.hasOwnProperty.call(_store, k) ? _store[k] : null),
+	setItem: (k, v) => { _store[k] = String(v); },
+	removeItem: k => { delete _store[k]; },
+};
+globalThis.esc = s => String(s);
+globalThis.t = k => k;
+globalThis.pysimFsFilterRender = () => { _renders++; };
+globalThis.pysimFsRenderTree = () => { _treeRenders++; };
+
+let code = '';
+for (const f of ['servicesFeatureByNumber', 'pysimFsFilterBtnHtml', 'pysimFsSetFilterToService']) {
+	code += extractFunc(html, f) + '\n';
+}
+for (const c of ['SERVICES_CROSS_REF', 'SERVICES_FS_MAP']) code += extractConst(html, c);
+eval(code);
+
+test('servicesFeatureByNumber inverts the cross-reference per file table', () => {
+	const map = servicesFeatureByNumber();
+	assert.strictEqual(map.ust[2], 'Fixed Dialling Numbers (FDN)');
+	assert.strictEqual(map.sst[2], 'Local Phone Book (ADN)');
+	assert.strictEqual(map.est[1], 'Fixed Dialling Numbers (FDN)');
+	assert.strictEqual(map.ist[1], 'P-CSCF address');
+	// the same number names a different feature in another table
+	assert.strictEqual(map.ust[1], 'Local Phone Book (ADN)');
+	assert.strictEqual(map.sst[1], 'CHV1 disable function');
+	// a capability-only number maps to a feature too
+	assert.strictEqual(map.ust[99], 'URI support by UICC');
+	// the map is built once
+	assert.strictEqual(servicesFeatureByNumber(), map);
+});
+
+test('pysimFsFilterBtnHtml links a file-backed service row only', () => {
+	const out = pysimFsFilterBtnHtml('ust', 2);
+	assert.match(out, /^<button type="button" class="ml-1 px-1 text-xs text-blue-600 dark:text-blue-400 hover:underline"/);
+	assert.ok(out.indexOf("pysimFsSetFilterToService('ust', 2)") > 0, out);
+	assert.ok(out.indexOf('To EF filter') > 0, out);
+	// OCI is file-backed
+	assert.notStrictEqual(pysimFsFilterBtnHtml('ust', 8), '');
+	// a capability-only service, a missing table and an unmodelled number
+	assert.strictEqual(pysimFsFilterBtnHtml('ust', 99), '');
+	assert.strictEqual(pysimFsFilterBtnHtml(undefined, 1), '');
+	assert.strictEqual(pysimFsFilterBtnHtml('sst', 99), '');
+});
+
+test('pysimFsSetFilterToService narrows the tree to that service', () => {
+	delete _store.simple_fs_filter;
+	_renders = 0;
+	_treeRenders = 0;
+	pysimFsFilter = new Set(['all']);
+	pysimFsSetFilterToService('ust', 2);
+	assert.deepStrictEqual([...pysimFsFilter], ['svc:Fixed Dialling Numbers (FDN)']);
+	assert.strictEqual(_store.simple_fs_filter, JSON.stringify(['svc:Fixed Dialling Numbers (FDN)']));
+	assert.strictEqual(_renders, 1);
+	assert.strictEqual(_treeRenders, 1);
+	// a capability-only service changes nothing
+	pysimFsSetFilterToService('ust', 99);
+	assert.deepStrictEqual([...pysimFsFilter], ['svc:Fixed Dialling Numbers (FDN)']);
+	assert.strictEqual(_renders, 1);
+	assert.strictEqual(_treeRenders, 1);
+});
+
+test('the four service-table fields carry their table, EF.ACC carries none', () => {
+	assert.match(html, /const EF_UST_FIELDS = \[\{[^\n]*table: 'ust'/);
+	assert.match(html, /const EF_IST_FIELDS = \[\{[^\n]*table: 'ist'/);
+	assert.match(html, /const EF_EST_FIELDS = \[\{[^\n]*table: 'est'/);
+	assert.match(html, /const EF_SST_FIELDS = \[\{[\s\S]{0,200}?table: 'sst'/);
+	const acc = /const EF_ACC_FIELDS = [^\n]*/.exec(html);
+	assert.ok(acc, 'EF_ACC_FIELDS not found');
+	assert.ok(acc[0].indexOf('table') < 0, acc[0]);
+});
+
+test('both service-grid renderers append the cross-link after their control', () => {
+	const fn = extractFunc(html, 'efDecFieldHtml');
+	assert.strictEqual((fn.match(/pysimFsFilterBtnHtml\(f\.table, n\)/g) || []).length, 2, fn);
+});