feat(creator): Refactor Creator flow, implement book creation pipeline & versioning, and setup Docker staging

- Relocate dashboard routing to /creator and editor workspace to /creator/edit/{BookId}
- Implement CreateBookCommand and handler with transactional default chapter seeding
- Implement PublishBookVersionCommand and GetCreatorDashboardDataQuery
- Build CreatorDashboard modal and UI components with customized dark input styles
- Add run-stage.sh script to automate staging environment setup, database migrations, and health checks
- Update developer workflow rules in GEMINI.md

src/NexusReader.Application/DTOs/Creator/CreatorDtos.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+
+namespace NexusReader.Application.DTOs.Creator;
+
+/// <summary>
+/// Telemetry metrics for the Creator Dashboard.
+/// </summary>
+public record DashboardMetricsDto(
+    int TotalReads,
+    double AvgReadTimeMinutes,
+    int ActiveReaders,
+    decimal GrossRevenue
+);
+
+/// <summary>
+/// Lightweight revision details for the Creator Dashboard.
+/// </summary>
+public record CreatorBookRevisionDto(
+    Guid Id,
+    string VersionString,
+    bool IsPublished,
+    DateTime CreatedAt,
+    DateTime? PublishedAt
+);
+
+/// <summary>
+/// Lightweight book publication details for the Creator Dashboard.
+/// </summary>
+public record CreatorBookDto(
+    Guid Id,
+    string Title,
+    int WordCount,
+    int AggregatedReads,
+    Guid? FirstChapterId,
+    CreatorBookRevisionDto? LivePublishedRevision,
+    CreatorBookRevisionDto? CurrentDraftRevision
+);
+
+/// <summary>
+/// Root data envelope for Creator Dashboard loading.
+/// </summary>
+public record CreatorDashboardDataDto(
+    DashboardMetricsDto Metrics,
+    List<CreatorBookDto> Books
+);
+
+/// <summary>
+/// Request DTO for creating a new Book.
+/// </summary>
+public record CreateBookRequestDto(
+    string Title,
+    string? Description
+);
+
+/// <summary>
+/// Response DTO for creating a new Book.
+/// </summary>
+public record CreateBookResponseDto(
+    Guid BookId
+);