feat: custom labels toggle and inline editing in product list

Adds session-based show/hide toggle for custom labels in admin product list, inline editable fields for custom_label_0..4, and label suggestions with custom entry support. Includes repository/controller updates, UI fixes, tests, and PAUL docs release updates.

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

.paul/codebase/testing.md

@@ -1,11 +1,11 @@
-# Testing Patterns
+# Testing Patterns
 
 ## Overview
 
 | Metric | Value |
 |--------|-------|
-| Total tests | **810** |
-| Total assertions | **2264** |
+| Total tests | **828** |
+| Total assertions | **2306** |
 | Framework | PHPUnit 9.6 (`phpunit.phar`) |
 | Bootstrap | `tests/bootstrap.php` |
 | Config | `phpunit.xml` |
@@ -13,7 +13,7 @@
 ## Running Tests
 
 ```bash
-# Full suite (PowerShell — recommended)
+# Full suite (PowerShell — recommended)
 ./test.ps1
 
 # Specific file
@@ -36,16 +36,16 @@ Tests mirror source structure:
 
 ```
 tests/Unit/
-├── Domain/
-│   ├── Product/ProductRepositoryTest.php
-│   ├── Category/CategoryRepositoryTest.php
-│   ├── Order/OrderRepositoryTest.php
-│   └── ... (all 29 modules covered)
-├── admin/Controllers/
-│   ├── ShopCategoryControllerTest.php
-│   └── ...
-└── api/
-    └── ...
+├── Domain/
+│   ├── Product/ProductRepositoryTest.php
+│   ├── Category/CategoryRepositoryTest.php
+│   ├── Order/OrderRepositoryTest.php
+│   └── ... (all 29 modules covered)
+├── admin/Controllers/
+│   ├── ShopCategoryControllerTest.php
+│   └── ...
+└── api/
+    └── ...
 ```
 
 ## Test Class Pattern
@@ -229,13 +229,13 @@ $this->assertInstanceOf(ClassName::class, $obj);
 
 ## What's Covered
 
-- All 29 Domain repositories ✓
-- Core business logic (quantity, pricing, category tree) ✓
-- Query behavior with mocked Medoo ✓
-- Cache patterns ✓
-- Controller constructor injection ✓
-- `FormValidator` behavior ✓
-- API controllers ✓
+- All 29 Domain repositories âś“
+- Core business logic (quantity, pricing, category tree) âś“
+- Query behavior with mocked Medoo âś“
+- Cache patterns âś“
+- Controller constructor injection âś“
+- `FormValidator` behavior âś“
+- API controllers âś“
 
 ## What's Lightly Covered
 
@@ -243,3 +243,4 @@ $this->assertInstanceOf(ClassName::class, $obj);
 - Session state in tests
 - AJAX response integration
 - Frontend Views (static classes)
+