feat: implement gRPC AgentService, Program.cs with Kestrel HTTP/2 config

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

@@ -0,0 +1,43 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using NexusRMM.Infrastructure.Data;
+
+namespace NexusRMM.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/[controller]")]
+public class AgentsController : ControllerBase
+{
+    private readonly RmmDbContext _db;
+    public AgentsController(RmmDbContext db) => _db = db;
+
+    [HttpGet]
+    public async Task<IActionResult> GetAll()
+    {
+        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 })
+            .ToListAsync();
+        return Ok(agents);
+    }
+
+    [HttpGet("{id:guid}")]
+    public async Task<IActionResult> GetById(Guid id)
+    {
+        var agent = await _db.Agents.FindAsync(id);
+        return agent is null ? NotFound() : Ok(agent);
+    }
+
+    [HttpGet("{id:guid}/metrics")]
+    public async Task<IActionResult> GetMetrics(Guid id, [FromQuery] int hours = 24)
+    {
+        var since = DateTime.UtcNow.AddHours(-hours);
+        var metrics = await _db.AgentMetrics
+            .Where(m => m.AgentId == id && m.Timestamp >= since)
+            .OrderByDescending(m => m.Timestamp)
+            .Take(1000)
+            .Select(m => new { m.Timestamp, m.Metrics })
+            .ToListAsync();
+        return Ok(metrics);
+    }
+}

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

@@ -0,0 +1,51 @@
+using System.Text.Json;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using NexusRMM.Core.Models;
+using NexusRMM.Infrastructure.Data;
+
+namespace NexusRMM.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/[controller]")]
+public class TasksController : ControllerBase
+{
+    private readonly RmmDbContext _db;
+    public TasksController(RmmDbContext db) => _db = db;
+
+    [HttpPost]
+    public async Task<IActionResult> Create([FromBody] CreateTaskRequest request)
+    {
+        var task = new TaskItem
+        {
+            Id = Guid.NewGuid(),
+            AgentId = request.AgentId,
+            Type = request.Type,
+            Payload = request.Payload is not null ? JsonSerializer.SerializeToElement(request.Payload) : null,
+            CreatedAt = DateTime.UtcNow
+        };
+        _db.Tasks.Add(task);
+        await _db.SaveChangesAsync();
+        return CreatedAtAction(nameof(GetById), new { id = task.Id }, task);
+    }
+
+    [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/Controllers/TicketsController.cs

@@ -0,0 +1,64 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using NexusRMM.Core.Models;
+using NexusRMM.Infrastructure.Data;
+
+namespace NexusRMM.Api.Controllers;
+
+[ApiController]
+[Route("api/v1/[controller]")]
+public class TicketsController : ControllerBase
+{
+    private readonly RmmDbContext _db;
+    public TicketsController(RmmDbContext db) => _db = db;
+
+    [HttpGet]
+    public async Task<IActionResult> GetAll([FromQuery] TicketStatus? status = null)
+    {
+        var query = _db.Tickets.AsQueryable();
+        if (status.HasValue) query = query.Where(t => t.Status == status.Value);
+        var tickets = await query.OrderByDescending(t => t.CreatedAt).Take(100).ToListAsync();
+        return Ok(tickets);
+    }
+
+    [HttpGet("{id:int}")]
+    public async Task<IActionResult> GetById(int id)
+    {
+        var ticket = await _db.Tickets.Include(t => t.Agent).FirstOrDefaultAsync(t => t.Id == id);
+        return ticket is null ? NotFound() : Ok(ticket);
+    }
+
+    [HttpPost]
+    public async Task<IActionResult> Create([FromBody] CreateTicketRequest request)
+    {
+        var ticket = new Ticket
+        {
+            Title = request.Title,
+            Description = request.Description,
+            Priority = request.Priority,
+            AgentId = request.AgentId,
+            CreatedAt = DateTime.UtcNow,
+            UpdatedAt = DateTime.UtcNow
+        };
+        _db.Tickets.Add(ticket);
+        await _db.SaveChangesAsync();
+        return CreatedAtAction(nameof(GetById), new { id = ticket.Id }, ticket);
+    }
+
+    [HttpPut("{id:int}")]
+    public async Task<IActionResult> Update(int id, [FromBody] UpdateTicketRequest request)
+    {
+        var ticket = await _db.Tickets.FindAsync(id);
+        if (ticket is null) return NotFound();
+        if (request.Status.HasValue) ticket.Status = request.Status.Value;
+        if (request.Priority.HasValue) ticket.Priority = request.Priority.Value;
+        if (request.Title is not null) ticket.Title = request.Title;
+        if (request.Description is not null) ticket.Description = request.Description;
+        ticket.UpdatedAt = DateTime.UtcNow;
+        await _db.SaveChangesAsync();
+        return Ok(ticket);
+    }
+}
+
+public record CreateTicketRequest(string Title, string Description, TicketPriority Priority, Guid? AgentId);
+public record UpdateTicketRequest(string? Title, string? Description, TicketStatus? Status, TicketPriority? Priority);