feat(map): adopt cooperative gestures to stop trapping page scroll

[markdumay]

Problem

Leaflet binds the wheel to zoom and a single finger to pan. Scrolling the page with the
pointer over a map therefore gets swallowed and the page sticks — the classic embedded-map scroll
trap. It reproduces today on
gethinode.com/docs/components/map: a plain wheel over
the map takes the tiles from zoom 13 to 12 instead of scrolling the page.

This is the same trap gethinode/mod-mermaid#338 removed from inline diagrams in v4.10.0. That PR
described its goal as following "the cooperative-gesture pattern used by embedded maps" — so this
restores the pattern to the map it was named after.

Change

The map now claims only a gesture that is unambiguously meant for it:

Gesture	Before	After
Wheel over map	zooms map (page sticks)	page scrolls, hint appears
Ctrl/⌘ + wheel	page zooms	map zooms
Mouse drag	pans map	pans map (unchanged)
One finger	pans map (page sticks)	page scrolls, hint appears
Two fingers	—	pans / pinch-zooms map
+/−, keyboard	zooms	unchanged

A gesture the map ignores briefly shows an overlay — "Use ⌘ + scroll to zoom the map" — so an
ignored gesture does not read as a broken map.

How it works

Every listener runs in the capture phase. Leaflet binds its own handlers deeper in the tree, so
stopping the event here (wheel without a modifier) or withdrawing the handler here (dragging
during a one-finger touch) settles the gesture before Leaflet ever sees it. With the modifier held
the event is simply let through, so Leaflet applies its own tuned zoom rather than a reimplementation
of it.

Notable details

• The hint stays translatable. The shortcode renders it into data-leaflet-hint-*; only the
  modifier is resolved in the browser, since it depends on the visitor's platform (⌘ vs Ctrl).
  Adds i18n/ for the eight languages Hinode ships, and the i18n mount, which the module lacked.
• The stylesheet slot. dist/leaflet.scss is Leaflet's vendored CSS, regenerated by
  postinstall, and it occupied the module's single assets/scss/leaflet.scss slot — so the overlay
  styles had nowhere to live. It is remounted as leaflet-vendor.scss, and a hand-written
  assets/scss/leaflet.scss imports it and adds the overlay. The vendored file stays untouched.
• The overlay class keeps the leaflet- prefix that Hinode's PurgeCSS safelist (/^leaflet-/)
  already covers, and is pointer-events: none + aria-hidden — it is advisory and must never
  swallow the gesture it is explaining.
• No new shortcode argument: cooperative behaviour is always on. An opt-out would just be a way to
  reintroduce the bug.

Verification

Driven in a real browser against the block reference, with the module replaced locally into a
Hinode host:

Check	Result
Plain wheel over map	tiles stay at z13, hint shown ✅
Ctrl + wheel	tiles go to z12 ✅
{modifier} placeholder	resolved to ⌘ on macOS ✅
Overlay styles compiled	position: absolute, scrim, pointer-events: none ✅
Vendored Leaflet CSS still applied	container styled, 28 tiles loaded ✅

pnpm test passes.

Review notes

The seven non-English translations are mine and have not been reviewed by a native speaker —
worth a look, particularly zh-hans/zh-hant. The hint timing (2s) and the dark scrim are easy to
adjust.

🤖 Generated with Claude Code

[markdumay]

🎉 This PR is included in version 3.1.0 🎉

The release is available on GitHub release

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