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).

tests/Novelly.Api.Tests/ImportServiceTests.cs

@@ -1,4 +1,5 @@
 using System.Threading.Channels;
+using Microsoft.Extensions.Options;
 using Novelly.Api.Imports;
 using Novelly.Api.Novels;
 
@@ -20,6 +21,8 @@ public class ImportServiceTests : ServiceTestFixture
             Novels,
             _queue,
             UserContext,
+            Options.Create(new ImportOptions()),
+            new ImportZipExtractor(new CapturingLogger<ImportZipExtractor>()),
             new CapturingLogger<ImportService>(),
             new InspectImportRequestValidator(),
             new StartImportRequestValidator());
@@ -32,6 +35,12 @@ public class ImportServiceTests : ServiceTestFixture
         {
             Directory.Delete(_root, recursive: true);
         }
+
+        var staging = Path.Combine(Path.GetTempPath(), "novelly-import-staging");
+        if (Directory.Exists(staging))
+        {
+            Directory.Delete(staging, recursive: true);
+        }
     }
 
     [Test]
@@ -131,6 +140,71 @@ public class ImportServiceTests : ServiceTestFixture
         });
     }
 
+    [Test]
+    public async Task Starting_an_import_outside_a_configured_import_root_is_rejected()
+    {
+        var configuredRoot = Directory.CreateTempSubdirectory("novelly-import-root-").FullName;
+        try
+        {
+            var restricted = new ImportService(
+                Db.Context,
+                Novels,
+                _queue,
+                UserContext,
+                Options.Create(new ImportOptions { RootPath = configuredRoot }),
+                new ImportZipExtractor(new CapturingLogger<ImportZipExtractor>()),
+                new CapturingLogger<ImportService>(),
+                new InspectImportRequestValidator(),
+                new StartImportRequestValidator());
+
+            Assert.That(
+                async () => await restricted.StartOrResumeAsync(new StartImportRequest(_root)),
+                Throws.TypeOf<ArgumentException>());
+        }
+        finally
+        {
+            Directory.Delete(configuredRoot, recursive: true);
+        }
+    }
+
+    [Test]
+    public async Task Starting_an_import_of_a_single_markdown_file_stages_it_into_a_folder()
+    {
+        var file = Path.Combine(_root, "01-chapter.md");
+        File.WriteAllText(file, "# Chapter 1");
+
+        var job = await _imports.StartOrResumeAsync(new StartImportRequest(file));
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(Directory.Exists(job.SourceRoot), Is.True);
+            Assert.That(File.Exists(Path.Combine(job.SourceRoot, "01-chapter.md")), Is.True);
+        });
+    }
+
+    [Test]
+    public async Task Starting_an_import_of_the_same_single_file_twice_dedupes_to_the_same_staged_job()
+    {
+        var file = Path.Combine(_root, "01-chapter.md");
+        File.WriteAllText(file, "# Chapter 1");
+
+        var first = await _imports.StartOrResumeAsync(new StartImportRequest(file));
+        var second = await _imports.StartOrResumeAsync(new StartImportRequest(file));
+
+        Assert.That(second.Id, Is.EqualTo(first.Id));
+    }
+
+    [Test]
+    public async Task Starting_an_import_of_a_non_markdown_file_is_rejected()
+    {
+        var file = Path.Combine(_root, "notes.txt");
+        File.WriteAllText(file, "not markdown");
+
+        Assert.That(
+            async () => await _imports.StartOrResumeAsync(new StartImportRequest(file)),
+            Throws.TypeOf<ArgumentException>());
+    }
+
     private void WriteChapterFiles(int count)
     {
         var outlines = Path.Combine(_root, "outlines");