Add zip upload and mapped-path picker for outline import

Sandbox source paths under a configured Imports:RootPath, browse it
from the web dialog, upload a zip that extracts into staging, and
import a single markdown file (agent infers chapter vs character).

src/Novelly.Api/Imports/ImportService.cs

@@ -1,5 +1,6 @@
 using System.Threading.Channels;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
 using Novelly.Api.Common;
 using Novelly.Api.Common.Validation;
 using Novelly.Api.Data;
@@ -13,10 +14,34 @@ public class ImportService(
     NovelService novels,
     Channel<Guid> queue,
     INovelUserContext userContext,
+    IOptions<ImportOptions> importOptions,
+    ImportZipExtractor zipExtractor,
     ILogger<ImportService> logger,
     IModelValidator<InspectImportRequest> inspectValidator,
     IModelValidator<StartImportRequest> startValidator)
 {
+    private readonly string? _importRoot = importOptions.Value.RootPath is { } root ? Path.GetFullPath(root) : null;
+
+    public ImportUploadResponse UploadZip(Stream zipStream, string fileName)
+    {
+        if (_importRoot is null)
+            throw new InvalidOperationException("No import root is configured (Imports:RootPath).");
+
+        logger.LogInformation("Uploading import zip {FileName}", fileName);
+
+        Directory.CreateDirectory(_importRoot);
+        var stagingDir = Path.Combine(
+            ImportPaths.StagingRoot(_importRoot),
+            $"zip-{ImportPaths.SanitizeForFolderName(Path.GetFileNameWithoutExtension(fileName))}-{Guid.NewGuid():N}");
+
+        zipExtractor.Extract(zipStream, stagingDir);
+
+        var markdownCount = Directory.EnumerateFiles(stagingDir, "*.md", SearchOption.AllDirectories).Count();
+        var relativePath = Path.GetRelativePath(_importRoot, stagingDir).Replace(Path.DirectorySeparatorChar, '/');
+
+        return new ImportUploadResponse(stagingDir, relativePath, markdownCount);
+    }
+
     public Task<ImportInspectionResponse> InspectAsync(InspectImportRequest request, CancellationToken ct = default)
     {
         Guard.Null(request, nameof(request));
@@ -24,7 +49,7 @@ public class ImportService(
 
         logger.LogInformation("Inspecting import source {SourceRoot}", request.SourceRoot);
 
-        var root = ImportPaths.ResolveRoot(request.SourceRoot);
+        var root = ResolveSourceRoot(request.SourceRoot);
         var ledger = ImportPaths.ReadLedger(root);
         var total = ImportPaths.CountChapterFiles(root);
 
@@ -48,7 +73,7 @@ public class ImportService(
         logger.LogInformation(
             "Starting import for {SourceRoot}, forceRestart {ForceRestart}", request.SourceRoot, request.ForceRestart);
 
-        var root = ImportPaths.ResolveRoot(request.SourceRoot);
+        var root = ResolveSourceRoot(request.SourceRoot);
 
         if (request.ForceRestart)
         {
@@ -88,6 +113,40 @@ public class ImportService(
         return job;
     }
 
+    private string ResolveSourceRoot(string sourceRoot)
+    {
+        string full;
+        try
+        {
+            full = Path.GetFullPath(sourceRoot);
+        }
+        catch (Exception ex) when (ex is ArgumentException or NotSupportedException or PathTooLongException)
+        {
+            throw new ArgumentException($"'{sourceRoot}' is not a valid path.", nameof(sourceRoot), ex);
+        }
+
+        if (!File.Exists(full))
+        {
+            return ImportPaths.ResolveRoot(sourceRoot, _importRoot);
+        }
+
+        if (!full.EndsWith(".md", StringComparison.OrdinalIgnoreCase))
+            throw new ArgumentException($"'{sourceRoot}' is not a markdown file or a directory.", nameof(sourceRoot));
+
+        ImportPaths.EnsureWithinImportRoot(_importRoot, full, sourceRoot);
+
+        var stagingParent = _importRoot is not null
+            ? ImportPaths.StagingRoot(_importRoot)
+            : Path.Combine(Path.GetTempPath(), "novelly-import-staging");
+        var stagingDir = Path.Combine(
+            stagingParent, $"file-{ImportPaths.SanitizeForFolderName(Path.GetFileNameWithoutExtension(full))}");
+
+        Directory.CreateDirectory(stagingDir);
+        File.Copy(full, Path.Combine(stagingDir, Path.GetFileName(full)), overwrite: true);
+
+        return stagingDir;
+    }
+
     public async Task<ImportJob?> GetStatusAsync(Guid id, CancellationToken ct = default)
     {
         Guard.Default(id, nameof(id));