Add background-hash-mark addition for region routing

Per https://buymeacoffee.com/ripplebiz/region-filtering:

> After some discussions, and that there is some confusion
around #channels and #regions, it's been decided to drop
the requirement to have the '#' prefix. So, region names
will just be plain alphanumeric (and '-'), with no # prefix.

> For backwards compatibility, the names will internally have
a '#' prepended, but for all client GUI's and command lines,
you generally won't see mention of '#' prefixes. The next
firmware release (v1.12.0) and subsequent Ripple firmware
and Liam's app will have modified UI to remove the '#' requirement.

So, silently add, but don't duplicate, for users who have already
added hashmarks.

tests/test_channels_router.py

@@ -270,7 +270,7 @@ class TestChannelFloodScopeOverride:
         with patch("app.routers.channels.broadcast_event") as mock_broadcast:
             response = await client.post(
                 f"/api/channels/{key}/flood-scope-override",
-                json={"flood_scope_override": "#Esperance"},
+                json={"flood_scope_override": "Esperance"},
             )
 
         assert response.status_code == 200
@@ -283,6 +283,20 @@ class TestChannelFloodScopeOverride:
         mock_broadcast.assert_called_once()
         assert mock_broadcast.call_args.args[0] == "channel"
 
+    @pytest.mark.asyncio
+    async def test_existing_hash_is_not_doubled(self, test_db, client):
+        key = "CC" * 16
+        await ChannelRepository.upsert(key=key, name="#flightless", is_hashtag=True)
+
+        response = await client.post(
+            f"/api/channels/{key}/flood-scope-override",
+            json={"flood_scope_override": "#Esperance"},
+        )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["flood_scope_override"] == "#Esperance"
+
     @pytest.mark.asyncio
     async def test_blank_override_clears_channel_flood_scope_override(self, test_db, client):
         key = "BB" * 16

tests/test_radio.py

@@ -655,6 +655,40 @@ class TestPostConnectSetupOrdering:
 
         mock_mc.commands.set_flood_scope.assert_awaited_once_with("#TestRegion")
 
+    @pytest.mark.asyncio
+    async def test_plain_flood_scope_is_normalized_during_setup(self):
+        """Legacy/plain stored flood_scope is normalized before applying to radio."""
+        from app.models import AppSettings
+        from app.radio import RadioManager
+
+        rm = RadioManager()
+        mock_mc = MagicMock()
+        mock_mc.start_auto_message_fetching = AsyncMock()
+        mock_mc.commands.set_flood_scope = AsyncMock()
+        rm._meshcore = mock_mc
+
+        mock_settings = AppSettings(flood_scope="TestRegion")
+
+        with (
+            patch("app.event_handlers.register_event_handlers"),
+            patch("app.keystore.export_and_store_private_key", new_callable=AsyncMock),
+            patch("app.radio_sync.sync_radio_time", new_callable=AsyncMock),
+            patch(
+                "app.repository.AppSettingsRepository.get",
+                new_callable=AsyncMock,
+                return_value=mock_settings,
+            ),
+            patch("app.radio_sync.sync_and_offload_all", new_callable=AsyncMock, return_value={}),
+            patch("app.radio_sync.start_periodic_sync"),
+            patch("app.radio_sync.send_advertisement", new_callable=AsyncMock, return_value=False),
+            patch("app.radio_sync.start_periodic_advert"),
+            patch("app.radio_sync.drain_pending_messages", new_callable=AsyncMock, return_value=0),
+            patch("app.radio_sync.start_message_polling"),
+        ):
+            await rm.post_connect_setup()
+
+        mock_mc.commands.set_flood_scope.assert_awaited_once_with("#TestRegion")
+
     @pytest.mark.asyncio
     async def test_flood_scope_empty_resets_during_setup(self):
         """Empty flood_scope calls set_flood_scope("") during post_connect_setup."""

tests/test_send_messages.py

@@ -279,8 +279,8 @@ class TestOutgoingChannelBroadcast:
         mc = _make_mc(name="MyNode")
         chan_key = "de" * 16
         await ChannelRepository.upsert(key=chan_key, name="#flightless")
-        await ChannelRepository.update_flood_scope_override(chan_key, "#Esperance")
-        await AppSettingsRepository.update(flood_scope="#Baseline")
+        await ChannelRepository.update_flood_scope_override(chan_key, "Esperance")
+        await AppSettingsRepository.update(flood_scope="Baseline")
 
         with (
             patch("app.routers.messages.require_connected", return_value=mc),
@@ -303,8 +303,8 @@ class TestOutgoingChannelBroadcast:
         mc = _make_mc(name="MyNode")
         chan_key = "df" * 16
         await ChannelRepository.upsert(key=chan_key, name="#matching")
-        await ChannelRepository.update_flood_scope_override(chan_key, "#Esperance")
-        await AppSettingsRepository.update(flood_scope="#Esperance")
+        await ChannelRepository.update_flood_scope_override(chan_key, "Esperance")
+        await AppSettingsRepository.update(flood_scope="Esperance")
 
         with (
             patch("app.routers.messages.require_connected", return_value=mc),

tests/test_settings_router.py

@@ -55,7 +55,7 @@ class TestUpdateSettings:
     @pytest.mark.asyncio
     async def test_flood_scope_round_trip(self, test_db):
         """Flood scope should be saved and retrieved correctly."""
-        result = await update_settings(AppSettingsUpdate(flood_scope="#MyRegion"))
+        result = await update_settings(AppSettingsUpdate(flood_scope="MyRegion"))
         assert result.flood_scope == "#MyRegion"
 
         fresh = await AppSettingsRepository.get()
@@ -70,7 +70,13 @@ class TestUpdateSettings:
     @pytest.mark.asyncio
     async def test_flood_scope_whitespace_stripped(self, test_db):
         """Flood scope should be stripped of whitespace."""
-        result = await update_settings(AppSettingsUpdate(flood_scope="  #MyRegion  "))
+        result = await update_settings(AppSettingsUpdate(flood_scope="  MyRegion  "))
+        assert result.flood_scope == "#MyRegion"
+
+    @pytest.mark.asyncio
+    async def test_flood_scope_existing_hash_is_not_doubled(self, test_db):
+        """Existing leading hash should be preserved for backward compatibility."""
+        result = await update_settings(AppSettingsUpdate(flood_scope="#MyRegion"))
         assert result.flood_scope == "#MyRegion"
 
     @pytest.mark.asyncio
@@ -92,7 +98,7 @@ class TestUpdateSettings:
         mock_rm.radio_operation = mock_radio_op
 
         with patch("app.radio.radio_manager", mock_rm):
-            await update_settings(AppSettingsUpdate(flood_scope="#TestRegion"))
+            await update_settings(AppSettingsUpdate(flood_scope="TestRegion"))
 
         mock_mc.commands.set_flood_scope.assert_awaited_once_with("#TestRegion")