fix(logo-threads): Y-align to cross logo (#21)

* fix(pulse): split halves now meet simultaneously + no backtracking

Two bugs fixed after Linus feedback:

1. Path-form: top/bottom split halves used Bezier curves that could
   loop back on themselves when entry.x lay outside box X-range.
   Now use clamped startX/endX (max(xL+r, min(xR-r, entry.x))) so
   pathen alltid rör sig framåt (entry.x → exit.x), aldrig vänder.

2. Synchronized meeting: previously each blob moved at fixed velocity
   along its own path → shorter path arrived first and waited.
   Now both blobs share a phase2T (0→1) progress fraction, so they
   meet at exit-point simultaneously. The path with different length
   simply moves at a slightly different speed (averaged). Phase2
   duration based on avg(topLen,bottomLen)/velocity so total animation
   time stays consistent.

* feat: logo-pulse with pink->green color transition

Adds a 4th pulse target: the IMAGES BY OLOFSSON hero-text logo.
20% chance per pulse-slot when logo is visible (footer scrolled in).

Flow:
1. New purple wave-thread on bottom-left (mirror of cyan wave1 on right)
2. Pulse glides in along purple thread to logo-left edge
3. Pulse enters logo + tints smoky-path stroke pink (#e879f9) + adds
   pink text-shadow halo on h1
4. Mid-passage: tint transitions to green (#4fd1c5) — matches default
   smoke + cyan glow
5. Pulse exits logo via wave1 (existing cyan thread on right)
6. Logo tint reverts to default (white smokeShift animation)

CSS-side: data-logo-tint attribute on #text-wrapper drives stroke +
text-shadow overrides with 0.6-0.8s transitions for smooth fade.

* fix(logo-pulse): dynamic paths anchored to logo + 50% probability

Previous version tried to use existing wave1+threadPurple paths for
logo-pulse glide-in/out, but those paths are in SVG-fixed coordinates
that don't align with logo's viewport position when hero is scrolled
into view. wave1 has translateX(2283) which pushes it off-screen for
ultrawide viewports.

Fix: build dynamic Bezier paths anchored to the logo's actual
getBoundingClientRect() position at pulse-time:
- Entry path: from (offLeft, logoY+dipOffset) curves up into logo-left
- Exit path: from logo-right curves up to (offRight, logoY-riseOffset)

Paths are appended to box-trail-group, used for one pulse, then
removed in cleanup. No reliance on fixed wave-thread coordinates.

Also raises LOGO_PROBABILITY 20%->50% so the effect is visible more
often when hero is in view.

* fix(logo-pulse): visible entry/exit threads + restore pulse color after

Two bugs fixed:

1. Entry+exit paths were stroke=transparent — pulse appeared to spawn
   out of nothing. Now stroke=url(#gradPurple) on entry (subtle pink
   thread visible from off-screen left) and stroke=url(#gradMain) on
   exit (cyan thread visible going off-screen right). Both at
   stroke-width 0.8 + opacity 0.55 to match other wave-thread style.

2. After logo-pulse completed, pulse-gradient stops were left in pink
   state — next regular wave-pulse rendered as stale pink instead of
   cyan/theme color. Now updatePulseColors(false) is called in cleanup
   to restore default cyan-tema.

* fix(logo-pulse): entry/exit threads now properly visible

Previous version used gradient strokes (gradPurple/gradMain) which
have stop-opacity 0 at ends + 0.45 mid, multiplied by path-opacity
0.55 = ~0.25 effective opacity. Practically invisible.

Now solid stroke colors (#e879f9 pink, #4fd1c5 cyan), stroke-width 2
(was 0.8), opacity 0.85 (was 0.55), plus pulseGlowMid filter for soft
halo. Should be clearly visible from off-screen edges to logo.

* feat(logo-pulse): permanent visible threads (no dynamic creation)

Previously dynamic paths were built/destroyed per pulse, were too
thick (stroke-width 2 + glow), and persisted incorrectly causing
visual artifacts.

Now:
- threadLogoIn: permanent purple wave-thread, same style as other
  wave-threads (gradPurple stroke, stroke-width 0.7, opacity 0.55)
- threadLogoOut: permanent cyan wave-thread (gradMain stroke 0.7,
  opacity 0.50)
- runLogoPulse uses these permanent paths via getPointAtLength
- getScreenCTM converts SVG-coords to screen-coords so pulse follows
  thread even with scroll/viewport variance

* fix(logo-threads): align Y-coords to actually cross logo

Logo Y-center is approx 287 in screen-coords. Previous thread Y-coords
(400-600) only grazed logo-bottom or sat entirely below it. Adjusted:

- threadLogoIn: M-1000 500 Q 200 350 850 287 T 2600 200
  Kommer från nedre-vänster (Y=500), kurvar UPP till logo-center
  (Y=287), fortsätter upp till övre-höger (Y=200)
- threadLogoOut: M-1000 350 Q 400 200 850 287 T 2600 500
  Kommer från övre-vänster (Y=350), genom logo-center (Y=287), ner
  till nedre-höger (Y=500) — vertikalt motsatt entry-tråd

src/components/WaveBackground.astro

@@ -72,8 +72,8 @@ const pulseCore = theme === 'purple' ? '#fdf4ff' : '#f0fdfa';
             <path id="thread1" d="M-1000 200 Q 400 400 900 200 T 2600 200" fill="none" stroke="url(#gradSec)" stroke-width="0.5" class="opacity-50" data-pulse-path="true" />
             <path id="thread2" d="M-1000 800 Q 600 600 1100 800 T 2600 800" fill="none" stroke="url(#gradSec)" stroke-width="0.8" class="opacity-60" data-pulse-path="true" />
 
-            <path id="threadLogoIn" d="M-1000 400 Q 400 600 900 400 T 2600 400" fill="none" stroke="url(#gradPurple)" stroke-width="0.7" class="opacity-55" />
-            <path id="threadLogoOut" d="M-1000 600 Q 400 400 900 600 T 2600 600" fill="none" stroke="url(#gradMain)" stroke-width="0.7" class="opacity-50" />
+            <path id="threadLogoIn" d="M-1000 500 Q 200 350 850 287 T 2600 200" fill="none" stroke="url(#gradPurple)" stroke-width="0.7" class="opacity-55" />
+            <path id="threadLogoOut" d="M-1000 350 Q 400 200 850 287 T 2600 500" fill="none" stroke="url(#gradMain)" stroke-width="0.7" class="opacity-50" />
         </g>
 
         <g id="box-trail-group"></g>