refactor: Extract zoom drag handlers to functions in zoom._hs

- Move inline drag handling (~35 lines) to external functions (~4 lines)
- Add isZoomDragTarget(el), startZoomDrag(), moveZoomDrag(), endZoomDrag()
- Note: 'target' is reserved in hyperscript, use 'el' for parameters
- Drag state stored on element (_isDragging, _initialX, _initialY)

Zoom control HTML now has clean, minimal hyperscript handlers.

templates/partials/widgets/zoom-control.html

@@ -2,39 +2,9 @@
 <!-- Zoom Control (Fixed Bottom Center, Draggable) - Hyperscript Enhanced -->
 <div id="zoom-control" class="zoom-control no-print zoom-hidden" role="group" aria-label="{{if eq .Lang "es"}}Control de zoom{{else}}Zoom control{{end}}"
      _="on load call initZoomControl(me)
-
-        on mousedown(clientX, clientY)
-          set target to event.target
-          set tag to target.tagName
-          if tag is 'INPUT' or tag is 'BUTTON' then exit end
-          if target.classList.contains('zoom-slider') or target.classList.contains('zoom-close-btn') or target.classList.contains('zoom-reset-btn') or target.classList.contains('zoom-value') then exit end
-          if target.closest('.zoom-close-btn') or target.closest('.zoom-reset-btn') then exit end
-          set :isDragging to true
-          set my *transition to 'none'
-          set rect to my getBoundingClientRect()
-          set :initialX to clientX - rect.left
-          set :initialY to clientY - rect.top
-          halt the event
-
-        on mousemove(clientX, clientY) from document
-          if :isDragging is not true then exit end
-          halt the event
-          set currentX to clientX - :initialX
-          set currentY to clientY - :initialY
-          set maxX to window.innerWidth - my offsetWidth
-          set maxY to window.innerHeight - my offsetHeight
-          set currentX to Math.max(0, Math.min(currentX, maxX))
-          set currentY to Math.max(0, Math.min(currentY, maxY))
-          set my *left to `${currentX}px`
-          set my *bottom to `${window.innerHeight - currentY - my offsetHeight}px`
-          set my *transform to 'none'
-
-        on mouseup from document
-          if :isDragging is not true then exit end
-          set :isDragging to false
-          set my *transition to 'all 0.3s ease'
-          set position to { bottom: my *bottom, left: my *left }
-          set localStorage['cv-zoom-position'] to JSON.stringify(position)">
+        on mousedown(clientX, clientY) if isZoomDragTarget(event.target) call startZoomDrag(me, clientX, clientY) then halt the event end
+        on mousemove(clientX, clientY) from document if moveZoomDrag(me, clientX, clientY) halt the event end
+        on mouseup from document call endZoomDrag(me)">
 
     <button
         id="zoom-close"