chore(backend): add explicit test data seed command

docs/TASKS/content/003-real-workspace-channels.md

@@ -12,7 +12,7 @@ Replace frontend-derived fake channels with real workspace-owned channel records
 
 - Add a backend `Channels` module with a `Channel` table.
 - Add list and create endpoints for workspace channels.
-- Seed development channels and align seeded content publication targets to those configured channel names.
+- Seed test channels and align seeded content publication targets to those configured channel names.
 - Update the frontend channels store to load and create channels through the API.
 - Keep the Channels page UI shape intact.
 
@@ -20,7 +20,7 @@ Replace frontend-derived fake channels with real workspace-owned channel records
 
 - `backend/src/Socialize.Api/Data/AppDbContext.cs`
 - `backend/src/Socialize.Api/Modules/Channels/`
-- `backend/src/Socialize.Api/Infrastructure/Development/DevelopmentSeedExtensions.cs`
+- `backend/src/Socialize.Api/Infrastructure/TestData/TestDataSeedExtensions.cs`
 - `frontend/src/features/channels/stores/channelsStore.js`
 - `docs/FEATURES/channels.md`
 

docs/TASKS/development/001-script-testdata-seed.md

@@ -0,0 +1,20 @@
+# Task: Add explicit test data seed script
+
+## Goal
+
+Move demo/test data seeding out of API startup and into an explicit script command that can be run intentionally against any configured environment.
+
+## Relevant Files
+
+- `backend/src/Socialize.Api/Program.cs`
+- `backend/src/Socialize.Api/Infrastructure/TestData/TestDataSeedExtensions.cs`
+- `backend/src/Socialize.Api/appsettings.Development.json`
+- `backend/src/Socialize.Api/appsettings.Production.json`
+- `scripts/seed-testdata.sh`
+
+## Validation
+
+```bash
+dotnet build backend/Socialize.slnx
+./scripts/seed-testdata.sh
+```