add subtle player-tile highlight on nation hover

The hover wiring already pushed setHighlightOwner into the border pass,
but the WebGL canvas has pointer-events: none (post-migration to the
inputOverlay div) so MapInteraction's pointermove listener never fired.
Forward pointermove from the input overlay to view.handlePointerMove
so hover actually triggers.

While there, brighten every tile owned by the hovered player — the
territory frag shader now reads uHighlightOwner / uHighlightBrighten
and mixes toward white when the tile owner matches. Wired through
territory-pass.ts; renderer.setHighlightOwner forwards to both border
and territory passes. New highlightFillBrighten setting (0.15) keeps
the fill tint tunable independently of the existing highlightBrighten
border setting, which is dropped from 0.6 → 0.25 so neither effect
blows out.

src/client/render/gl/render-settings.json

@@ -65,7 +65,8 @@
     "emberColorBrightG": 0.5,
     "emberColorBrightB": 0.05,
     "emberStrengthUnowned": 0.5,
-    "highlightBrighten": 0.6,
+    "highlightBrighten": 0.25,
+    "highlightFillBrighten": 0.15,
     "highlightThicken": 2,
     "defensePostRange": 30,
     "embargoTintRatio": 0.35,