fix: Add region search filter + pre-select on edit + create plan doc

## ✅ Issue #1: TAX_NOTIFICATIONS_PLAN.md Created
- Complete implementation plan for Tax & Notifications
- 80/20 rule: Core features vs Advanced (WooCommerce)
- API endpoints defined
- Implementation phases prioritized

## ✅ Issue #2: Region Search Filter
- Added search input above region list
- Real-time filtering as you type
- Shows "No regions found" when no matches
- Clears search on dialog close/cancel
- Makes finding countries/states MUCH faster!

## ✅ Issue #3: Pre-select Regions on Edit
- Backend now returns raw `locations` array
- Frontend uses `defaultChecked` with location matching
- Existing regions auto-selected when editing zone
- Works correctly for countries, states, and continents

## UX Improvements:
- Search placeholder: "Search regions..."
- Filter is case-insensitive
- Empty state when no results
- Clean state management (clear on close)

Now zone editing is smooth and fast!

TAX_NOTIFICATIONS_PLAN.md

@@ -0,0 +1,106 @@
+# Tax & Notifications Implementation Plan
+
+## Philosophy: 80/20 Rule - Real Value, Not Menu-ing
+
+WooNooW provides elegant UX for 80% of daily use cases.
+The 20% advanced/rare features stay in WooCommerce.
+
+---
+
+## Tax Settings - What to Build
+
+### Core Features (80% use cases):
+
+1. **Enable/Disable Tax Calculation**
+   - Simple toggle
+   - Clear explanation
+
+2. **Tax Rates by Country/State**
+   - Add/Edit/Delete tax rates
+   - Country selector
+   - State selector (for countries with states)
+   - Rate percentage input
+   - Tax class selector (Standard, Reduced, Zero)
+
+3. **Prices Include Tax Toggle**
+   - "Prices entered with tax" vs "without tax"
+   - Clear explanation
+
+4. **Display Settings**
+   - Show prices in shop: including/excluding tax
+   - Show prices in cart: including/excluding tax
+   - Display suffix (e.g., "incl. VAT")
+
+### Advanced Features (Link to WooCommerce):
+
+- Complex tax classes (rare)
+- Compound taxes (rare)
+- Tax based on shipping vs billing (advanced)
+- Custom tax tables (very rare)
+
+---
+
+## Notifications Settings - What to Build
+
+### Core Features (80% use cases):
+
+1. **Email Enable/Disable**
+   - Toggle for each email type
+   - Already implemented ✅
+
+2. **Edit Email Subjects**
+   - Inline editing of subject lines
+   - Variables support ({order_number}, {site_title})
+
+3. **Sender Configuration**
+   - "From" name
+   - "From" email address
+
+4. **Email Preview**
+   - Preview button for each email
+   - Opens WooCommerce preview
+
+### Advanced Features (Link to WooCommerce):
+
+- Full HTML template editing (advanced)
+- Custom email templates (developer)
+- Header/footer customization (advanced)
+- Additional recipients (rare)
+
+---
+
+## Implementation Priority
+
+### Phase 1: Tax Rates (High Impact)
+1. Backend: Tax rates CRUD API
+2. Frontend: Tax rates list + Add/Edit dialog
+3. Frontend: Enable/disable toggle
+4. Frontend: Prices include tax toggle
+
+### Phase 2: Email Subjects (High Impact)
+1. Backend: Get/update email settings API
+2. Frontend: Sender name/email inputs
+3. Frontend: Inline subject editing
+4. Frontend: Preview links
+
+### Phase 3: Tax Display Settings (Medium Impact)
+1. Frontend: Display settings card
+2. Backend: Save display preferences
+
+---
+
+## API Endpoints Needed
+
+### Tax:
+- GET /settings/tax/rates
+- POST /settings/tax/rates
+- PUT /settings/tax/rates/{id}
+- DELETE /settings/tax/rates/{id}
+- GET /settings/tax/config
+- POST /settings/tax/config
+
+### Notifications:
+- GET /settings/notifications/emails
+- POST /settings/notifications/emails/{id}
+- GET /settings/notifications/sender
+- POST /settings/notifications/sender