docs: clarify database workflow and update folder structure

- Explain database migration workflow in copilot-instructions.md
- Detail three use cases: clone & run, recreate, Docker
- Remove obsolete Data/ database path references

Author: nanotaboada

.github/copilot-instructions.md

@@ -294,11 +294,26 @@ dotnet ef database update --project src/Dotnet.Samples.AspNetCore.WebApi
 ./scripts/run-migrations-and-copy-database.sh
 ```
 
-**Important**: The `run-migrations-and-copy-database.sh` script:
-- Resets the placeholder database file
-- Runs all migrations
-- Copies the generated database from `bin/Debug/net8.0/storage/` to `storage/`
-- Requires `dotnet ef` CLI tool installed globally
+**Database Workflow Explained:**
+
+The project maintains a **pre-seeded database** at `storage/players-sqlite3.db` to support three use cases:
+1. **Clone & Run** - Developers can clone the repo and run immediately without manual DB setup
+2. **Recreate from Scratch** - Use the script to rebuild the database with all migrations
+3. **Docker** - Container gets a copy of the pre-seeded database on first startup
+
+**How `run-migrations-and-copy-database.sh` works:**
+1. **Creates empty file** at `storage/players-sqlite3.db` (version-controlled source location)
+2. **Runs migrations** via `dotnet ef database update`
+   - EF Core uses `AppContext.BaseDirectory/storage/players-sqlite3.db`
+   - During migration, `AppContext.BaseDirectory` = `bin/Debug/net8.0/`
+   - EF Core creates/updates database at `bin/Debug/net8.0/storage/players-sqlite3.db`
+   - Applies all migrations: creates schema, seeds 26 players (11 starting + 15 substitutes)
+3. **Copies migration-applied database** from `bin/Debug/net8.0/storage/` back to `storage/`
+   - Updates the version-controlled database with latest schema + seed data
+   - This file is included in git and copied to build output via `.csproj` configuration
+
+**Requirements:**
+- `dotnet ef` CLI tool installed globally (`dotnet tool install --global dotnet-ef`)
 
 ### Docker Operations
 ```bash

README.md

@@ -75,7 +75,7 @@ src/Dotnet.Samples.AspNetCore.WebApi/
 │   ├── Player.cs
 │   ├── PlayerRequestModel.cs
 │   └── PlayerResponseModel.cs
-├── Data/                       # EF Core DbContext
+├── Data/                       # EF Core DbContext and migrations
 │   └── PlayerDbContext.cs
 ├── Mappings/                   # AutoMapper profiles
 │   └── PlayerMappingProfile.cs