feat: implement Phase 6 — Software Deployment

Backend:
- SoftwarePackage model (Name, Version, OsType, PackageManager, PackageName, InstallerUrl, Checksum, SilentArgs)
- RmmDbContext: SoftwarePackages DbSet + unique index on (Name, Version, OsType)
- SoftwarePackagesController: full CRUD with OsType filter
- DeployController: POST /api/v1/deploy creates InstallSoftware/UninstallSoftware TaskItem
- EF Migration: AddSoftwarePackages (20260319130448)

Go Agent:
- internal/deployer/deployer.go: Install() and Uninstall() with:
  - Chocolatey (Windows), apt/dnf (Linux), auto-detect
  - Direct installer fallback: HTTP download + SHA256 verify + silent install
  - Supports .msi, .exe (Windows) and .deb, .rpm (Linux)
- main.go: COMMAND_TYPE_INSTALL_SOFTWARE and COMMAND_TYPE_UNINSTALL_SOFTWARE routed to deployer

Frontend:
- SoftwarePage: Katalog tab (CRUD, OS filter, smart package manager select) + Deploy tab
- api/types.ts: SoftwarePackage, PackageManager, DeployRequest/Response types
- api/client.ts: softwarePackagesApi and deployApi
- App.tsx: Software nav item with Package icon

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

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

@@ -0,0 +1,63 @@
+using System.Text.Json;
+using Microsoft.AspNetCore.Mvc;
+using NexusRMM.Core.Models;
+using NexusRMM.Infrastructure.Data;
+
+namespace NexusRMM.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/deploy")]
+public class DeployController : ControllerBase
+{
+    private readonly RmmDbContext _db;
+    public DeployController(RmmDbContext db) => _db = db;
+
+    /// <summary>
+    /// Startet Software-Deployment auf einem Agent.
+    /// Erstellt einen TaskItem mit Typ InstallSoftware/UninstallSoftware.
+    /// </summary>
+    [HttpPost]
+    public async Task<IActionResult> Deploy([FromBody] DeployRequest req)
+    {
+        var agent = await _db.Agents.FindAsync(req.AgentId);
+        if (agent is null) return NotFound(new { error = "Agent nicht gefunden" });
+
+        var pkg = await _db.SoftwarePackages.FindAsync(req.PackageId);
+        if (pkg is null) return NotFound(new { error = "Paket nicht gefunden" });
+
+        var payload = new
+        {
+            packageName = pkg.PackageName,
+            packageManager = pkg.PackageManager,
+            installerUrl = pkg.InstallerUrl ?? "",
+            checksum = pkg.Checksum ?? "",
+            silentArgs = pkg.SilentArgs ?? "",
+            displayName = pkg.Name,
+            version = pkg.Version,
+        };
+
+        var task = new TaskItem
+        {
+            Id = Guid.NewGuid(),
+            AgentId = req.AgentId,
+            Type = req.Action == "uninstall" ? TaskType.UninstallSoftware : TaskType.InstallSoftware,
+            Payload = JsonSerializer.SerializeToElement(payload),
+            CreatedAt = DateTime.UtcNow,
+        };
+
+        _db.Tasks.Add(task);
+        await _db.SaveChangesAsync();
+
+        return CreatedAtAction(nameof(Deploy), new { id = task.Id }, new
+        {
+            task.Id,
+            task.AgentId,
+            task.Type,
+            task.Status,
+            PackageName = pkg.Name,
+            Version = pkg.Version,
+        });
+    }
+}
+
+public record DeployRequest(Guid AgentId, int PackageId, string Action); // Action: "install" | "uninstall"

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

@@ -0,0 +1,85 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using NexusRMM.Core.Models;
+using NexusRMM.Infrastructure.Data;
+
+namespace NexusRMM.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/software-packages")]
+public class SoftwarePackagesController : ControllerBase
+{
+    private readonly RmmDbContext _db;
+    public SoftwarePackagesController(RmmDbContext db) => _db = db;
+
+    [HttpGet]
+    public async Task<IActionResult> GetAll([FromQuery] OsType? osType = null)
+    {
+        var q = _db.SoftwarePackages.AsQueryable();
+        if (osType.HasValue) q = q.Where(p => p.OsType == osType.Value);
+        return Ok(await q.OrderBy(p => p.Name).ToListAsync());
+    }
+
+    [HttpGet("{id:int}")]
+    public async Task<IActionResult> GetById(int id)
+    {
+        var pkg = await _db.SoftwarePackages.FindAsync(id);
+        return pkg is null ? NotFound() : Ok(pkg);
+    }
+
+    [HttpPost]
+    public async Task<IActionResult> Create([FromBody] CreateSoftwarePackageRequest req)
+    {
+        var pkg = new SoftwarePackage
+        {
+            Name = req.Name,
+            Version = req.Version,
+            OsType = req.OsType,
+            PackageManager = req.PackageManager,
+            PackageName = req.PackageName,
+            InstallerUrl = req.InstallerUrl,
+            Checksum = req.Checksum,
+            SilentArgs = req.SilentArgs,
+        };
+        _db.SoftwarePackages.Add(pkg);
+        await _db.SaveChangesAsync();
+        return CreatedAtAction(nameof(GetById), new { id = pkg.Id }, pkg);
+    }
+
+    [HttpPut("{id:int}")]
+    public async Task<IActionResult> Update(int id, [FromBody] CreateSoftwarePackageRequest req)
+    {
+        var pkg = await _db.SoftwarePackages.FindAsync(id);
+        if (pkg is null) return NotFound();
+        pkg.Name = req.Name;
+        pkg.Version = req.Version;
+        pkg.OsType = req.OsType;
+        pkg.PackageManager = req.PackageManager;
+        pkg.PackageName = req.PackageName;
+        pkg.InstallerUrl = req.InstallerUrl;
+        pkg.Checksum = req.Checksum;
+        pkg.SilentArgs = req.SilentArgs;
+        await _db.SaveChangesAsync();
+        return Ok(pkg);
+    }
+
+    [HttpDelete("{id:int}")]
+    public async Task<IActionResult> Delete(int id)
+    {
+        var pkg = await _db.SoftwarePackages.FindAsync(id);
+        if (pkg is null) return NotFound();
+        _db.SoftwarePackages.Remove(pkg);
+        await _db.SaveChangesAsync();
+        return NoContent();
+    }
+}
+
+public record CreateSoftwarePackageRequest(
+    string Name,
+    string Version,
+    OsType OsType,
+    string PackageManager,
+    string PackageName,
+    string? InstallerUrl,
+    string? Checksum,
+    string? SilentArgs);