Move Proclamations From Sub-Categories To Groups

The portal's v2 API replaced nested categories (proclamation_categories.parent_id)
with flat categories plus tag-like groups: a proclamation now belongs to one
category and optionally one group. This lets the Proclamation Options page drop
its special-cased two-level tree.

Database:
- Add the proclamation_groups table (id, name, sort_order) and a
  proclamations.group_id column.
- Drop parent_id from the proclamation_categories DDL so fresh databases get a
  flat table.
- runMigrations() creates the new table/column, then runs a one-time
  transactional v1->v2 migration keyed on PRAGMA user_version: every legacy
  sub-category becomes a group (its id is preserved), proclamations that
  pointed at a sub-category are remapped to (parent category, new group), and
  the now-stale sub-category rows are deleted. selected flags are never
  touched, so user choices survive. No network is needed, so offline kiosks
  migrate at startup; re-running is a no-op.
- Add replaceGroups() and getAllGroups(); stop reading/writing parent_id.

API sync:
- Add PATH_GROUPS ("/groups") and parseGroupsJson().
- parseProclamationsJson() now also reads groupId.
- syncProclamationsFromApi() fetches /proclamations, /categories and /groups,
  leaves the database untouched if any request or parse fails, then replaces
  categories, replaces groups and upserts proclamations.

Proclamation Options page:
- FlatItem is now Category / Group / Proclamation.
- Each category lists only the groups that have at least one member in that
  category, so impossible pairings (e.g. Physical/Prayers) never render.
- Proclamations with no group, or with a group the portal has removed, sit
  directly under the category. Groups are collapsible and use a distinct color.

Tests:
- test_db: groups round-trip plus a legacy->v2 migration test asserting the
  group is created, proclamations are remapped, selection is preserved and a
  second initialize() is a no-op.
- test_proclamation_sync / test_api_client: parse groupId, parse groups, and
  the live smoke test now also fetches /groups.

Docs: README database table and AGENTS notes updated for groups.

tests/test_api_client.cpp

@@ -142,16 +142,25 @@ TEST(ApiClientTest, ParseProclamationsToleratesLegacyLevelField) {
     EXPECT_EQ(out[1].category_id, 32);
 }
 
-TEST(ApiClientTest, ParseCategoriesHandlesNullParentId) {
-    const std::string body =
-        R"([{"id":4,"name":"Spiritual","sortOrder":0,"parentId":null},
-            {"id":5,"name":"General","sortOrder":0,"parentId":4}])";
+TEST(ApiClientTest, ParseFlatCategoriesAndGroups) {
+    const std::string categoriesBody =
+        R"([{"id":4,"name":"Spiritual","sortOrder":0},
+            {"id":5,"name":"General","sortOrder":1}])";
 
-    std::vector<radiantwave::db::ProclamationCategoryRecord> out;
-    EXPECT_TRUE(radiantwave::sync::parseCategoriesJson(body, out));
-    ASSERT_EQ(out.size(), 2u);
-    EXPECT_EQ(out[0].parent_id, 0); // null parentId maps to 0 (root)
-    EXPECT_EQ(out[1].parent_id, 4);
+    std::vector<radiantwave::db::ProclamationCategoryRecord> categories;
+    EXPECT_TRUE(radiantwave::sync::parseCategoriesJson(categoriesBody, categories));
+    ASSERT_EQ(categories.size(), 2u);
+    EXPECT_EQ(categories[0].id, 4);
+    EXPECT_EQ(categories[1].id, 5);
+
+    const std::string groupsBody =
+        R"([{"id":9,"name":"Prayers","sortOrder":0}])";
+
+    std::vector<radiantwave::db::ProclamationGroupRecord> groups;
+    EXPECT_TRUE(radiantwave::sync::parseGroupsJson(groupsBody, groups));
+    ASSERT_EQ(groups.size(), 1u);
+    EXPECT_EQ(groups[0].id, 9);
+    EXPECT_EQ(groups[0].name, "Prayers");
 }
 
 // ─── Live: GET /frequencies (harmless, always runs) ───────────────────
@@ -194,7 +203,15 @@ TEST(ApiClientLiveTest, ProclamationsAndCategoriesLiveSmoke) {
 
     std::vector<radiantwave::db::ProclamationCategoryRecord> categories;
     EXPECT_TRUE(radiantwave::sync::parseCategoriesJson(catsResponse.body, categories));
-    EXPECT_GE(categories.size(), 20u);
+    EXPECT_FALSE(categories.empty());
+
+    HttpResponse groupsResponse = httpGet(PATH_GROUPS);
+    ASSERT_TRUE(groupsResponse.transportOk);
+    ASSERT_EQ(groupsResponse.status, 200);
+
+    std::vector<radiantwave::db::ProclamationGroupRecord> groups;
+    EXPECT_TRUE(radiantwave::sync::parseGroupsJson(groupsResponse.body, groups));
+    EXPECT_FALSE(groups.empty());
 }
 
 // ─── Live: POST /license error paths (no credentials required) ─────────