feat(reader): touch selection handles, copy fallback, highlight tap editing

- Custom drag handles (start/end) for post-lift selection adjustment:
  the native handles are disabled with the rest of the native touch
  selection controller; these are positioned at the selection's
  boundary carets and driven through the same clamped caret mapping
- Copy button falls back to execCommand via a transient textarea on
  plain HTTP (navigator.clipboard is unavailable on LAN addresses);
  both paths clear the selection and dismiss the popover
- Only dismiss the selection popover on actual position changes in
  relocate (detail.section is a fresh object on every relocate, so
  reference comparison always saw a move); a tap's no-op relocate
  was closing the just-opened highlight edit popover
- Pin foliate-js f872a01 (synthetic click dispatch on quick taps)
  and 422e8e0 (don't snap taps that never panned)

package.json

@@ -12,7 +12,7 @@
     "dev": "npm run build:ts:dev && npm run build:css"
   },
   "dependencies": {
-    "@bookhoard/foliate-js": "git+https://github.com/john-okeefe/foliate-js.git#9cfe266929ba650438d908253671a75a42dc4ccf",
+    "@bookhoard/foliate-js": "git+https://github.com/john-okeefe/foliate-js.git#422e8e0",
     "alpinejs": "^3.15.8",
     "chart.js": "^4.5.1",
     "highlight.js": "^11.11.1",