feat(paginator): manual touch scrolling in scrolled layouts — kill the native fling

Scrolled (webtoon) layouts now scroll single-finger drags manually, the
same path paginated layouts always used: the browser's native touch
scrolling — and its fling momentum — is suppressed so the full gesture
stream stays observable to hosts. The reader's chrome UX (bookhoard
handoff item 7) classifies vertical flicks from that stream: flick-down
reveals, down/up dismisses. Side-swipes in paginated layouts and drags
in scrolled ones both page/scroll exactly as before, minus momentum.

Release behavior in scrolled layouts is stop-where-released — no snap,
deliberately: webtoon panels don't align to screen boundaries and a
snap would fight zoomed panning. Long jumps stay the position UI's
job. Pinch zoom, multi-touch, and active touch selection keep their
native behavior via the existing guards (they return before the
preventDefault). Desktop wheel scrolling is untouched.

Version 0.5.4.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "foliate-js",
-  "version": "0.5.3",
+  "version": "0.5.4",
   "description": "Render e-books in the browser",
   "repository": {
     "type": "git",

paginator.js

@@ -986,7 +986,14 @@ export class Paginator extends HTMLElement {
         const state = this.#touchState
         if (state.pinched) return
         state.pinched = globalThis.visualViewport.scale > 1
-        if (this.scrolled || state.pinched) return
+        // Scrolled layouts (webtoon) scroll MANUALLY, like paginated ones:
+        // the browser's native touch scrolling — and its fling momentum —
+        // is suppressed so the full gesture stream stays observable to
+        // hosts (the reader classifies vertical flicks as chrome-reveal).
+        // Momentum is deliberately absent: drags are 1:1 and stop dead on
+        // release (no snap — webtoon panels don't align to screen
+        // boundaries); long jumps go through the reader's position UI.
+        if (state.pinched) return
         if (this.#touchSelActive) return
         if (e.touches.length > 1) {
             if (this.#touchScrolled) e.preventDefault()
@@ -1008,11 +1015,14 @@ export class Paginator extends HTMLElement {
     #onTouchEnd() {
         const wasScrolled = this.#touchScrolled
         this.#touchScrolled = false
-        if (this.scrolled || this.#touchSelActive) return
+        if (this.#touchSelActive) return
         // A touch that never panned (a tap) is already page-aligned;
         // snapping anyway emits a no-op relocate, which readers treat
         // as a page turn (e.g. dismissing a just-opened popover).
         if (!wasScrolled) return
+        // No velocity paging in scrolled layouts: content stays exactly
+        // where released.
+        if (this.scrolled) return
 
         // XXX: Firefox seems to report scale as 1... sometimes...?
         // at this point I'm basically throwing `requestAnimationFrame` at