Adds a `debounceStrategy` property to both PointOfSalePurchasableItemFetchStrategy and PointOfSaleCouponFetchStrategy protocols with default implementations returning `.immediate`.

This allows each fetch strategy implementation to declare its optimal debouncing behavior:
- Remote search strategies can use `.smart()` for network latency
- Local search strategies can use `.simple()` with loading delay thresholds
- Default strategies use `.immediate` for no debouncing

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Co-Authored-By: Claude <[email protected]>

Implements the debouncing strategy pattern in the search UI layer:

- Adds `debounceStrategy` property to POSSearchable protocol
- Updates POSSearchField's onChange handler to execute different debouncing logic based on strategy:
  - `.smart`: Skip debounce on first keystroke, debounce subsequent
  - `.simple`: Always debounce, with optional delayed loading indicators
  - `.immediate`: No debouncing
- Adds `currentDebounceStrategy` to item and coupon controllers to expose fetch strategy's debouncing behavior
- Implements protocol conformance in POSProductSearchable, POSOrderListView, and preview helpers

The `.simple` strategy with loading delay threshold prevents flicker on fast local searches by only showing loading indicators if the search exceeds the threshold duration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Implements `.simple(duration: 150ms, loadingDelayThreshold: 300ms)` for local GRDB product searches.

This strategy:
- Always debounces every keystroke by 150ms to prevent excessive queries
- Delays showing loading indicators until 300ms threshold is exceeded
- Prevents loading flicker for fast local searches (< 300ms)
- Only shows loading indicators for slower searches (> 300ms)

The combination of debouncing with delayed loading provides a responsive feel while avoiding visual flickering on fast local database queries.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Adds comprehensive test coverage for the debouncing strategy pattern:

- Tests for SearchDebounceStrategy enum equality
- Tests verifying each fetch strategy returns the correct debouncing behavior:
  - Local product search: `.simple` with loading delay threshold
  - Remote product search: `.smart` for network latency
  - Coupon search: `.smart` for network latency
  - Default strategies: `.immediate` for no debouncing

Tests ensure the debouncing strategies are correctly configured across all search types for optimal UX.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Update mocks to conform to PointOfSaleSearchingItemsControllerProtocol
which now requires currentDebounceStrategy property.

Adds optional loading delay threshold parameter to smart debounce strategy.
This enables delayed loading indicators for fast local searches to prevent
flicker, while maintaining immediate loading indicators for remote searches.

Changes:
- Add optional loadingDelayThreshold parameter to SearchDebounceStrategy.smart case
- Update POSSearchView to handle smart strategy with optional threshold:
  - Check for non-empty search term before showing loading (prevents loading on initial view)
  - Reset didFinishSearch to true when search view appears (ensures first search shows loading)
  - First keystroke without threshold: Show loading immediately (remote searches)
  - First keystroke with threshold: Delay loading until threshold or completion (local searches)
  - Subsequent keystrokes: Debounce request, loading already showing
- Remote searches use .smart without threshold for immediate responsive feedback
- Local searches use .simple with threshold to prevent flicker on fast queries
- Update test expectations to match strategy configurations

Fixes:
- No loading indicators shown when opening search view with popular products
- Loading indicators show immediately on first search keystroke for remote searches
- Local searches avoid flicker by only showing loading if query takes longer than threshold

The issue was that the debounce strategy was determined by the current
fetch strategy, but the fetch strategy didn't change from "popular products"
to "search" until performSearch() was called. This meant the first keystroke
used the `.immediate` strategy from popular products, which set
`didFinishSearch=false` but didn't call `clearSearchResults()` to show loading.

Solution: Added `searchDebounceStrategy` property to POSSearchable protocol
that returns the debounce strategy that will be used for searches, regardless
of the current fetch mode. The onChange handler now captures this strategy
synchronously before creating the Task, ensuring we use the search strategy
(.smart) from the very first keystroke.

Changes:
- Added `searchDebounceStrategy` to POSSearchable protocol
- Updated POSSearchView to use searchDebounceStrategy for non-empty searches
- Implemented searchDebounceStrategy in controllers by creating temporary
  search strategy to query its debounce settings
- Updated all mocks and preview helpers to conform to new protocol

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

The POSSearchable protocol had two confusingly named properties:
- debounceStrategy: The currently active strategy
- searchDebounceStrategy: The strategy that will be used for searches

Renamed debounceStrategy → currentDebounceStrategy to make the
distinction clear: currentDebounceStrategy reflects what's active
right now, while searchDebounceStrategy reflects what will be used
when searching.

This improves code readability without changing any behavior.

…-1112-configurable-search-debounce-strategies