Add Formula Library ratings, Job Profitability report, and Quote Revision History improvements

- Formula Library ratings: thumbs up/down per company per formula; toggle on/off; sorts by net score; own formulas not rateable; FormulaLibraryRating entity + migration AddFormulaLibraryRatings
- Job Profitability report: actual labor cost (logged hours x StandardLaborRate) vs powder cost vs billed price per job; gross margin % color-coded; time-tracked-only filter; totals footer
- Quote Revision History: track Total price changes on every save; log Sent/Resent events with recipient email; replace flat table with grouped timeline UI (icons per event type, total-change badge on header)
- Setup Wizard: cap CompletedCount at TotalSteps so old 10-step data no longer shows 10/5
- Formula Library card: fix badge overflow on long titles; add Rate: label to make voting buttons discoverable
- Help docs and AI knowledge base updated for all three features

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -295,6 +295,9 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Per-company record of which community library formulas a company has imported.</summary>
     public DbSet<FormulaLibraryImport> FormulaLibraryImports { get; set; }
 
+    /// <summary>Per-company thumbs-up / thumbs-down vote on community library formulas.</summary>
+    public DbSet<FormulaLibraryRating> FormulaLibraryRatings { get; set; }
+
     /// <summary>User-submitted bug reports; tenant-filtered with soft delete.</summary>
     public DbSet<BugReport> BugReports { get; set; }
     /// <summary>File attachments for bug reports; soft-delete only (no tenant filter — access controlled via parent BugReport).</summary>
@@ -2116,6 +2119,18 @@ modelBuilder.Entity<Job>()
             .IsUnique()
             .HasDatabaseName("IX_FormulaLibraryImports_Company_Item");
 
+        // FormulaLibraryRating — platform-level; one vote per company per formula
+        modelBuilder.Entity<FormulaLibraryRating>()
+            .HasOne(r => r.FormulaLibraryItem)
+            .WithMany()
+            .HasForeignKey(r => r.FormulaLibraryItemId)
+            .OnDelete(DeleteBehavior.Cascade);
+
+        modelBuilder.Entity<FormulaLibraryRating>()
+            .HasIndex(r => new { r.FormulaLibraryItemId, r.CompanyId })
+            .IsUnique()
+            .HasDatabaseName("IX_FormulaLibraryRatings_Item_Company");
+
         // CustomItemTemplate → FormulaLibraryItem (nullable; only set on imported templates)
         modelBuilder.Entity<CustomItemTemplate>()
             .HasOne(t => t.SourceFormulaLibraryItem)