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.Core/Entities/FormulaLibraryRating.cs

@@ -0,0 +1,24 @@
+namespace PowderCoating.Core.Entities;
+
+/// <summary>
+/// One thumbs-up or thumbs-down vote per company per library formula.
+/// Platform-level — no BaseEntity, no soft delete, no CompanyId tenant filter.
+/// Unique constraint enforced at the DB level: (FormulaLibraryItemId, CompanyId).
+/// </summary>
+public class FormulaLibraryRating
+{
+    public int Id { get; set; }
+
+    public int FormulaLibraryItemId { get; set; }
+
+    /// <summary>The company casting the vote.</summary>
+    public int CompanyId { get; set; }
+
+    /// <summary>True = thumbs up, false = thumbs down.</summary>
+    public bool IsPositive { get; set; }
+
+    public DateTime RatedAt { get; set; } = DateTime.UtcNow;
+
+    // Navigation
+    public virtual FormulaLibraryItem FormulaLibraryItem { get; set; } = null!;
+}