feat(landing): hero refinements from the design prototype

[madansap]

Brings the hero work from the DevNepalFront prototype into the portal. Both
repos already run the same stack — Base UI 1.8, Phosphor, cn, shadcn 4.21,
three 0.178, Tailwind 4, Next 16, React 19 — so this is a graft, not a port:
no new dependencies.

First of a section-by-section pass over the landing page. Navbar and the
government masthead follow in their own PR.

What changed

• NepalMap — Nepal drawn as a feathered field of blueprint grid, from the
  same Natural Earth 50m boundary the globe already uses for its land mask.
  Pure SVG, no dependencies, sits behind the hero at -z-10.
• lib/layout.ts — sectionGutter / sectionPadding: one definition of
  the gutter and vertical rhythm the landing sections already shared by hand.
  The hero was the only section on py-16 rather than py-12 lg:py-16; it now
  lines up with members-section and project-spotlight-section.
• Globe height follows the viewport (clamp on 80svh) instead of a fixed
  26rem, so it fills tall screens without overflowing short ones.
• Globe alignment is now explicit. It used to infer its composition from the
  shape of its own box — "wide box, sit right of centre, leave room for the copy
  on the left". Below lg the hero stacks and that box is h-64 w-full, short
  and wide, so the rule fired exactly where it shouldn't and pushed the sphere
  to the right edge of a column with nothing beside it. Box shape cannot tell
  the two compositions apart (the desktop box is landscape too), so the caller
  decides: GlobeScene.setAlignment, driven by a media query on the same lg
  breakpoint at which the hero switches to two columns.
• Hero heading second line capitalized; page title and description updated
  to match.

Deliberately not taken from the prototype

• Its hero copy, which frames the portal as multi-ministry.
• Its CONTRIBUTORS naming for the globe waypoints.

Both were corrected on main and stay corrected. The prototype's
ui/button.tsx was also skipped — this repo's version is a superset, with the
nativeButton / render props the CTAs depend on.

Review fixes included

A review pass found and this PR fixes:

• setAlignment cleared the WebGL drawing buffer without painting the frame
  that every other resize() call site pairs with it. Masked in practice
  because crossing lg also changes the canvas box, so the ResizeObserver
  repainted — but with the hero scrolled out of view the frame loop is stopped
  and the canvas would have stayed blank. Camera framing is now its own step,
  applyViewOffset(), which touches no GPU buffer: an alignment change costs a
  projection matrix instead of a reallocated canvas, and it paints itself. Also
  removes two of the three resize() passes that ran during hero mount on
  mobile, and adds the disposed guard its sibling methods already had.
• NepalMap covered its box, so once the hero stacked, 76% of the map's
  width was cropped and what remained was an unreadable band of grid rather
  than Nepal. Measured at a 357×852 box before the fix; it fits the box now.

One design call worth a second opinion

Switching the map from slice to meet trades coverage for legibility: the
country is now whole at every width, but in the stacked layout it occupies a
band across ~28% of the hero's height rather than filling it. Correctness of the
shape won, since the component's whole premise is that this is Nepal — but if
you'd rather treat it as pure texture, it is one attribute to revert.

Known, deliberately left for later

• sectionGutter has one consumer; ten other call sites still hardcode the same
  gutter. Converting the rest belongs with the navbar/masthead PR, which touches
  those files anyway.
• The hero's calc(80svh - 15rem) encodes the combined height of the masthead,
  navbar and hero padding, with nothing linking them. A --site-chrome custom
  property is the right fix; also parked for the chrome PR.
• NepalMap's SVG ids are document-global. Harmless with one instance; needs
  useId() before a second.

Verification

bun run lint, typecheck, test (135 passing) and build all green.

Rendered and measured at 375, 820 and 1440, plus a live lg crossing at
1440→820 without a reload — the case the ResizeObserver was previously papering
over. Globe repaints centred, WebGL context alive.

🤖 Generated with Claude Code