Add new features and tests for AirGap and Time modules

- Introduced `SbomService` tasks documentation.
- Updated `StellaOps.sln` to include new projects: `StellaOps.AirGap.Time` and `StellaOps.AirGap.Importer`.
- Added unit tests for `BundleImportPlanner`, `DsseVerifier`, `ImportValidator`, and other components in the `StellaOps.AirGap.Importer.Tests` namespace.
- Implemented `InMemoryBundleRepositories` for testing bundle catalog and item repositories.
- Created `MerkleRootCalculator`, `RootRotationPolicy`, and `TufMetadataValidator` tests.
- Developed `StalenessCalculator` and `TimeAnchorLoader` tests in the `StellaOps.AirGap.Time.Tests` namespace.
- Added `fetch-sbomservice-deps.sh` script for offline dependency fetching.

src/AirGap/StellaOps.AirGap.Time/Controllers/TimeStatusController.cs

@@ -0,0 +1,64 @@
+using Microsoft.AspNetCore.Mvc;
+using StellaOps.AirGap.Time.Models;
+using StellaOps.AirGap.Time.Services;
+
+namespace StellaOps.AirGap.Time.Controllers;
+
+[ApiController]
+[Route("api/v1/time")]
+public class TimeStatusController : ControllerBase
+{
+    private readonly TimeStatusService _statusService;
+    private readonly TimeAnchorLoader _loader;
+
+    public TimeStatusController(TimeStatusService statusService, TimeAnchorLoader loader)
+    {
+        _statusService = statusService;
+        _loader = loader;
+    }
+
+    [HttpGet("status")]
+    public async Task<ActionResult<TimeStatusDto>> GetStatus([FromQuery] string tenantId)
+    {
+        if (string.IsNullOrWhiteSpace(tenantId))
+        {
+            return BadRequest("tenantId-required");
+        }
+
+        var status = await _statusService.GetStatusAsync(tenantId, DateTimeOffset.UtcNow, HttpContext.RequestAborted);
+        return Ok(TimeStatusDto.FromStatus(status));
+    }
+
+    [HttpPost("anchor")]
+    public async Task<ActionResult<TimeStatusDto>> SetAnchor([FromBody] SetAnchorRequest request)
+    {
+        if (!ModelState.IsValid)
+        {
+            return ValidationProblem(ModelState);
+        }
+
+        var trustRoot = new TimeTrustRoot(
+            request.TrustRootKeyId,
+            Convert.FromBase64String(request.TrustRootPublicKeyBase64),
+            request.TrustRootAlgorithm);
+
+        var result = _loader.TryLoadHex(
+            request.HexToken,
+            request.Format,
+            new[] { trustRoot },
+            out var anchor);
+
+        if (!result.IsValid)
+        {
+            return BadRequest(result.Reason);
+        }
+
+        var budget = new StalenessBudget(
+            request.WarningSeconds ?? StalenessBudget.Default.WarningSeconds,
+            request.BreachSeconds ?? StalenessBudget.Default.BreachSeconds);
+
+        await _statusService.SetAnchorAsync(request.TenantId, anchor, budget, HttpContext.RequestAborted);
+        var status = await _statusService.GetStatusAsync(request.TenantId, DateTimeOffset.UtcNow, HttpContext.RequestAborted);
+        return Ok(TimeStatusDto.FromStatus(status));
+    }
+}