Refactor parsers to Superpower; config set; EnsureManagedConfig; options doc

- Parsers: Superpower for all (Directive, FileLine, Include, DhcpHost, Leases, Hosts)
- Shared ConfParserHelpers (Token, OptionalCommentPrefix)
- DnsmasqConfOptionRegistry + DnsmasqOptionKind: typed options (ConfFile, ConfDir,
  Domain, DhcpRange, Server, Local, Address, DhcpOption, DhcpHost, Path, Flag, etc.)
- EnsureManagedConfigHostedService: append conf-dir= to main config if missing,
  then create managed file; DnsmasqOptions + Dockerfile comments for permissions
- Renames: ConfigLine->DnsmasqConfLine, ConfigSet->DnsmasqConfigSet, etc.
- Test harness: entrypoint in scripts/, prepare-test-mount improvements
- Status/Reload API and UI: stdout+stderr, exit code

src/DnsmasqWebUI/Controllers/ConfigController.cs

@@ -0,0 +1,69 @@
+using DnsmasqWebUI.Models;
+using DnsmasqWebUI.Services.Abstractions;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DnsmasqWebUI.Controllers;
+
+[ApiController]
+[Route("api/[controller]")]
+public class ConfigController : ControllerBase
+{
+    private readonly IDnsmasqConfigSetService _configSetService;
+    private readonly IDnsmasqConfigService _configService;
+    private readonly IReloadService _reloadService;
+
+    public ConfigController(IDnsmasqConfigSetService configSetService, IDnsmasqConfigService configService, IReloadService reloadService)
+    {
+        _configSetService = configSetService;
+        _configService = configService;
+        _reloadService = reloadService;
+    }
+
+    /// <summary>Returns the config set (main + conf-file/conf-dir) and managed file path. Read-only structure for UI.</summary>
+    [HttpGet("set")]
+    public async Task<ActionResult<DnsmasqConfigSet>> GetSet(CancellationToken ct)
+    {
+        try
+        {
+            var set = await _configSetService.GetConfigSetAsync(ct);
+            return Ok(set);
+        }
+        catch (Exception ex)
+        {
+            return StatusCode(500, new { error = ex.Message });
+        }
+    }
+
+    /// <summary>Returns the full content of the managed config file (parsed lines and effective addn-hosts path in file for display).</summary>
+    [HttpGet("managed")]
+    public async Task<ActionResult<ManagedConfigContent>> GetManaged(CancellationToken ct)
+    {
+        try
+        {
+            var content = await _configService.ReadManagedConfigAsync(ct);
+            return Ok(content);
+        }
+        catch (Exception ex)
+        {
+            return StatusCode(500, new { error = ex.Message });
+        }
+    }
+
+    /// <summary>Writes the full managed config file (ensures one addn-hosts line = HostsPath), then optionally triggers reload.</summary>
+    [HttpPut("managed")]
+    public async Task<ActionResult<object>> PutManaged([FromBody] List<DnsmasqConfLine>? lines, CancellationToken ct)
+    {
+        if (lines == null)
+            return BadRequest(new { error = "Body required" });
+        try
+        {
+            await _configService.WriteManagedConfigAsync(lines, ct);
+            var reload = await _reloadService.ReloadAsync(ct);
+            return Ok(new { saved = true, reload = new { reload.Success, reload.ExitCode, reload.StdErr } });
+        }
+        catch (Exception ex)
+        {
+            return StatusCode(500, new { error = ex.Message });
+        }
+    }
+}