fix: JSON-Serialisierung, API-Routing und Dark-Mode Dropdowns

Backend:
- Program.cs: JsonNamingPolicy.CamelCase + JsonStringEnumConverter global aktiviert
  → behebt alle Frontend-API-Calls (PascalCase statt camelCase, Integer statt String-Enums)
- AgentsController: GetMetrics nutzt jetzt 'limit' Parameter (statt 'hours')
  → Frontend-Aufruf ?limit=50 wird korrekt ausgewertet
- AgentsController: GetAll gibt MacAddress und EnrolledAt zurück
- TasksController: GET /tasks?agentId= Endpoint hinzugefügt
  → behebt Routing-Mismatch (Frontend nutzte Query-Parameter, Backend hatte Route-Parameter)

Frontend:
- SoftwarePage.tsx: Alle hardcodierten Hellmodus-Farben durch Theme-Variablen ersetzt
  (bg-white/gray → bg-card/muted, text-gray-* → text-foreground/muted-foreground)
- index.css: select option Stile für Dark-Mode Sichtbarkeit hinzugefügt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Backend/src/NexusRMM.Api/Controllers/AgentsController.cs

@@ -16,7 +16,7 @@ public class AgentsController : ControllerBase
     {
         var agents = await _db.Agents
             .OrderBy(a => a.Hostname)
-            .Select(a => new { a.Id, a.Hostname, a.OsType, a.OsVersion, a.IpAddress, a.Status, a.AgentVersion, a.LastSeen, a.Tags })
+            .Select(a => new { a.Id, a.Hostname, a.OsType, a.OsVersion, a.IpAddress, a.MacAddress, a.Status, a.AgentVersion, a.LastSeen, a.EnrolledAt, a.Tags })
             .ToListAsync();
         return Ok(agents);
     }
@@ -29,14 +29,13 @@ public class AgentsController : ControllerBase
     }
 
     [HttpGet("{id:guid}/metrics")]
-    public async Task<IActionResult> GetMetrics(Guid id, [FromQuery] int hours = 24)
+    public async Task<IActionResult> GetMetrics(Guid id, [FromQuery] int limit = 100)
     {
-        var since = DateTime.UtcNow.AddHours(-hours);
         var metrics = await _db.AgentMetrics
-            .Where(m => m.AgentId == id && m.Timestamp >= since)
+            .Where(m => m.AgentId == id)
             .OrderByDescending(m => m.Timestamp)
-            .Take(1000)
-            .Select(m => new { m.Timestamp, m.Metrics })
+            .Take(limit)
+            .Select(m => new { m.Id, m.AgentId, m.Timestamp, m.Metrics })
             .ToListAsync();
         return Ok(metrics);
     }

Backend/src/NexusRMM.Api/Controllers/TasksController.cs

@@ -29,23 +29,21 @@ public class TasksController : ControllerBase
         return CreatedAtAction(nameof(GetById), new { id = task.Id }, task);
     }
 
+    [HttpGet]
+    public async Task<IActionResult> GetAll([FromQuery] Guid? agentId = null)
+    {
+        var query = _db.Tasks.AsQueryable();
+        if (agentId.HasValue) query = query.Where(t => t.AgentId == agentId.Value);
+        var tasks = await query.OrderByDescending(t => t.CreatedAt).Take(50).ToListAsync();
+        return Ok(tasks);
+    }
+
     [HttpGet("{id:guid}")]
     public async Task<IActionResult> GetById(Guid id)
     {
         var task = await _db.Tasks.FindAsync(id);
         return task is null ? NotFound() : Ok(task);
     }
-
-    [HttpGet("agent/{agentId:guid}")]
-    public async Task<IActionResult> GetByAgent(Guid agentId)
-    {
-        var tasks = await _db.Tasks
-            .Where(t => t.AgentId == agentId)
-            .OrderByDescending(t => t.CreatedAt)
-            .Take(50)
-            .ToListAsync();
-        return Ok(tasks);
-    }
 }
 
 public record CreateTaskRequest(Guid AgentId, TaskType Type, object? Payload);

Backend/src/NexusRMM.Api/Program.cs

@@ -20,7 +20,12 @@ builder.Services.AddDbContext<RmmDbContext>(options =>
 
 builder.Services.AddGrpc();
 builder.Services.AddSignalR();
-builder.Services.AddControllers();
+builder.Services.AddControllers()
+    .AddJsonOptions(options =>
+    {
+        options.JsonSerializerOptions.PropertyNamingPolicy = System.Text.Json.JsonNamingPolicy.CamelCase;
+        options.JsonSerializerOptions.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());
+    });
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen();