Genericize the Schulware stateless contract's app-facing wire strings (#99)

The provider-agnostic app speaks generic headers/fields; the plugin's
internals and the plugin->SchulwareAPI hop stay Schulnetz.

- Data headers: X-Schulware-Token -> X-Plugin-Token,
  X-Schulnetz-Base-Url -> X-Provider-Base-Url.
- Stateless login/refresh body: schulnetzBaseUrl -> baseUrl.

Author: PianoNic

src/Schuly.Plugin.Schulware/Controllers/StatelessAuthController.cs

@@ -35,11 +35,11 @@ public class StatelessAuthController(
         public async Task<IActionResult> Login([FromBody] StatelessLoginRequest request)
         {
             var client = SchulwareApiClientFactory.Create(
-                httpClientFactory, BaseUrl, request.SchulnetzBaseUrl);
+                httpClientFactory, BaseUrl, request.BaseUrl);
 
             var result = await client.Api.Authenticate.Login.PostAsync(new LoginRequestDto
             {
-                SchulnetzBaseUrl = request.SchulnetzBaseUrl,
+                SchulnetzBaseUrl = request.BaseUrl,
                 Email = request.Email,
                 Password = request.Password,
                 TotpSecret = string.IsNullOrWhiteSpace(request.TotpSecret) ? null : request.TotpSecret,
@@ -74,7 +74,7 @@ public async Task<IActionResult> Refresh([FromBody] StatelessRefreshRequest requ
             var result = await client.Api.Authenticate.Refresh.PostAsync(
                 new RefreshTokenRequestDto
                 {
-                    SchulnetzBaseUrl = request.SchulnetzBaseUrl,
+                    SchulnetzBaseUrl = request.BaseUrl,
                     UserAgent = request.UserAgent,
                     ContextState = contextState,
                 });

src/Schuly.Plugin.Schulware/Controllers/StatelessDataController.cs

@@ -13,8 +13,8 @@ namespace Schuly.Plugin.Schulware.Controllers
     /// Stateless, account-free data proxy for the app's private mode. Fetches the
     /// caller's SchulwareAPI mobile data with their bearer token and returns it
     /// mapped to flat DTOs. Persists nothing. Credentials travel in headers:
-    /// <c>X-Schulware-Token</c> (the SchulwareAPI access token) and
-    /// <c>X-Schulnetz-Base-Url</c> (the school instance URL).
+    /// <c>X-Plugin-Token</c> (the access token) and
+    /// <c>X-Provider-Base-Url</c> (the school instance URL).
     /// </summary>
     [ApiController]
     [AllowAnonymous]
@@ -52,12 +52,12 @@ public Task<IActionResult> UserInfo() => ProxyAsync(async c =>
         /// </summary>
         private async Task<IActionResult> ProxyAsync<T>(Func<SchulwareApiClient, Task<T>> fetch)
         {
-            var token = Request.Headers["X-Schulware-Token"].ToString();
-            var schulnetzBaseUrl = Request.Headers["X-Schulnetz-Base-Url"].ToString();
+            var token = Request.Headers["X-Plugin-Token"].ToString();
+            var schulnetzBaseUrl = Request.Headers["X-Provider-Base-Url"].ToString();
             if (string.IsNullOrWhiteSpace(token))
-                return BadRequest("Missing X-Schulware-Token header");
+                return BadRequest("Missing X-Plugin-Token header");
             if (string.IsNullOrWhiteSpace(schulnetzBaseUrl))
-                return BadRequest("Missing X-Schulnetz-Base-Url header");
+                return BadRequest("Missing X-Provider-Base-Url header");
 
             try
             {

src/Schuly.Plugin.Schulware/Dtos/StatelessLoginRequest.cs

@@ -6,7 +6,7 @@ namespace Schuly.Plugin.Schulware.Dtos
     /// the <c>context_state</c> for the caller to persist on-device.
     /// </summary>
     public record StatelessLoginRequest(
-        string SchulnetzBaseUrl,
+        string BaseUrl,
         string Email,
         string Password,
         string? TotpSecret);

src/Schuly.Plugin.Schulware/Dtos/StatelessRefreshRequest.cs

@@ -8,7 +8,7 @@ namespace Schuly.Plugin.Schulware.Dtos
     /// exact WebView user agent back in on every refresh.
     /// </summary>
     public record StatelessRefreshRequest(
-        string SchulnetzBaseUrl,
+        string BaseUrl,
         string UserAgent,
         JsonElement ContextState);
 }