Add AI Quick Quote widget and inline customer reassignment

- New AI Quick Quote floating button: staff type a verbal description to
  get an instant price estimate for phone/walk-in customers; detected
  color names are fuzzy-matched against inventory for stock status;
  saves draft quote under a Walk-In / Phone customer with one click
- Inline customer change on Quote Details and Job Details: always-visible
  native select with inline confirmation banner (no TomSelect dependency);
  ChangeCustomer AJAX endpoints on QuotesController and JobsController
- Quote Edit page: customer dropdown is now editable (lock removed)
- Fix AutoMapper missing CatalogCategory -> UpdateCategoryDto mapping
  that caused a crash on the catalog category Edit page
- Help docs and AI knowledge base updated for all three features

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

src/PowderCoating.Web/Helpers/HelpKnowledgeBase.cs

@@ -226,6 +226,8 @@ public static class HelpKnowledgeBase
 
         **Downloading a quote PDF:** Quote Details page → "Download PDF" button.
 
+        **Changing the customer on a quote:** On the Quote Details page, the Customer field is an always-visible dropdown. Select a different customer — a confirmation banner appears asking you to confirm the change. Click **Save** to apply or **Cancel** to revert to the original. This is especially useful when a quote was created under the "Walk-In / Phone" placeholder and the real customer record is added later.
+
         ---
 
         ## JOBS
@@ -290,6 +292,8 @@ public static class HelpKnowledgeBase
 
         **Job Templates:** [/JobTemplates](/JobTemplates) — Save a job's items as a template to reuse for common work types. When creating a new job, select a template to pre-fill items.
 
+        **Changing the customer on a job:** On the Job Details page, the Customer field is an always-visible dropdown. Select a different customer — a confirmation banner appears. Click **Save** to apply or **Cancel** to revert. Use this to correct a misassigned job or to move a walk-in job to a customer's proper record after they've been added to the system.
+
         **Creating an invoice from a job:** On the Job Details page, look for the Invoice section and click "Create Invoice."
 
         **Blank Work Order:** Print a pre-formatted paper work order to hand to a walk-in customer before creating a digital job record.
@@ -1099,6 +1103,8 @@ public static class HelpKnowledgeBase
 
         10. **AI Help Assistant** — That's me! I can answer questions about how the system works.
 
+        11. **AI Quick Quote** — A floating button (visible on every page) that lets you get an instant rough estimate from a verbal description — ideal for phone calls and walk-in customers. Type a description such as "4 wheels, gloss black, need sandblasting", enter quantity and coat count, and the AI returns a price estimate with a confidence score. Detected color names are matched against your inventory so you can see at a glance whether you have the powder in stock. You can then save the quote under a "Walk-In / Phone" customer with one click and reassign it to the real customer record later. Access via the **dark-blue floating button** in the bottom-right corner, just above the AI Help button.
+
         **Plan availability:** AI Photo Quotes and AI Inventory Assist are enabled at the subscription plan level. If you do not see the AI Photo Quote option in the quote wizard or the AI lookup button on inventory items, the feature may not be included in your current plan. Contact your administrator or check [Billing](/Billing) to see your plan details.
 
         The AI Profile (in Company Settings) lets you describe your shop's specialties to improve AI quote estimates. This tab only appears when AI Photo Quotes are enabled for your account.
@@ -1119,6 +1125,9 @@ public static class HelpKnowledgeBase
         **Prospect to customer:**
         Create Quote for prospect → Quote Approved → Convert Prospect to Customer → Convert Quote to Job
 
+        **Walk-in / phone quote (quick estimate):**
+        Click the AI Quick Quote button (dark-blue floating button, bottom-right) → type description → AI returns price estimate → Save as draft under "Walk-In / Phone" → open the quote → reassign the Customer dropdown on Quote Details to the real customer record once you have their info
+
         **Purchase supplies:**
         Low stock alert on Dashboard → Create PO → Submit PO → Receive PO → Create Bill → Pay Bill