Fix frame deduplication and chronological ordering in time series endpoint

- Fix scraping to wait for display label to change after step forward, preventing duplicate minutesAgo values within same folder
- Add hashset-based deduplication by AbsoluteObservationTime across cache folders
- Filter frames that are too close together (< 4 minutes apart)
- Preserve original folder structure while pruning filtered frames
- Sort folders by earliest frame time to maintain chronological order
- Add validation to detect folder overlaps that could cause out-of-order frames

Controllers/CacheController.cs

@@ -0,0 +1,112 @@
+using BomLocalService.Models;
+using BomLocalService.Services.Interfaces;
+using BomLocalService.Utilities;
+using Microsoft.AspNetCore.Mvc;
+
+namespace BomLocalService.Controllers;
+
+[ApiController]
+[Route("api/cache")]
+public class CacheController : ControllerBase
+{
+    private readonly ICacheService _cacheService;
+    private readonly IBomRadarService _bomRadarService;
+    private readonly ILogger<CacheController> _logger;
+
+    public CacheController(
+        ICacheService cacheService, 
+        IBomRadarService bomRadarService,
+        ILogger<CacheController> logger)
+    {
+        _cacheService = cacheService;
+        _bomRadarService = bomRadarService;
+        _logger = logger;
+    }
+
+    /// <summary>
+    /// Get information about the available cache range for a location (oldest and newest cache folders).
+    /// Helps clients understand what historical data is available before requesting extended timespans.
+    /// </summary>
+    [HttpGet("{suburb}/{state}/range")]
+    public async Task<ActionResult<CacheRange>> GetCacheRange(string suburb, string state, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var validationError = ValidationHelper.ValidateLocation(suburb, state);
+            if (validationError != null)
+            {
+                return BadRequest(new { error = validationError });
+            }
+
+            var result = await _bomRadarService.GetCacheRangeAsync(suburb, state, cancellationToken);
+            
+            if (result.TotalCacheFolders == 0)
+            {
+                return NotFound(new { error = "No cached data found for this location." });
+            }
+            
+            return Ok(result);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error getting cache range for suburb: {Suburb}, state: {State}", suburb, state);
+            return StatusCode(500, new { error = "An error occurred while getting cache range", message = ex.Message });
+        }
+    }
+
+    /// <summary>
+    /// Manually trigger a cache refresh for a location. Returns status of the update operation.
+    /// </summary>
+    [HttpPost("{suburb}/{state}/refresh")]
+    public async Task<ActionResult<CacheUpdateStatus>> RefreshCache(string suburb, string state, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var validationError = ValidationHelper.ValidateLocation(suburb, state);
+            if (validationError != null)
+            {
+                return BadRequest(new { error = validationError });
+            }
+
+            var status = await _bomRadarService.TriggerCacheUpdateAsync(suburb, state, cancellationToken);
+            return Ok(status);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error triggering cache update for suburb: {Suburb}, state: {State}", suburb, state);
+            return StatusCode(500, new { error = "An error occurred while triggering cache update", message = ex.Message });
+        }
+    }
+
+    /// <summary>
+    /// Delete cached data for a location.
+    /// </summary>
+    [HttpDelete("{suburb}/{state}")]
+    public async Task<ActionResult> DeleteCache(string suburb, string state, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var validationError = ValidationHelper.ValidateLocation(suburb, state);
+            if (validationError != null)
+            {
+                return BadRequest(new { error = validationError });
+            }
+
+            var deleted = await _bomRadarService.DeleteCachedLocationAsync(suburb, state, cancellationToken);
+            
+            if (deleted)
+            {
+                return Ok(new { message = $"Cache deleted for {suburb}, {state}" });
+            }
+            else
+            {
+                return NotFound(new { error = $"No cached data found for {suburb}, {state}" });
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error deleting cached location for suburb: {Suburb}, state: {State}", suburb, state);
+            return StatusCode(500, new { error = "An error occurred while deleting cached location", message = ex.Message });
+        }
+    }
+}