Measure exoplanet inclination from the plane of the sky

The Exoplanet Archive measures orbital inclination from the plane of the sky —
the plane perpendicular to our line of sight to the host star. Ninety degrees
means edge-on as seen from Earth, which is why transiting planets pile up there:
1643 of the 2061 published inclinations are within five degrees of 90. The
renderer fed that straight into a propagator that reads inclination as an angle
from the reference plane, so every transiting system was tilted against a plane
its inclination was never measured against.

Each body's elements are now rotated out of their own reference plane into the
scene by a per-body quaternion. Solar-system elements keep the ecliptic rotation
from the previous commit. Exoplanets get a rotation carrying the elements' +Z
onto the line of sight to their host, which is exactly the star's own position —
so an inclination of i means the orbit's normal sits i from our line of sight,
which is the definition.

The rotation about that axis is the node's position angle on the sky. The
archive does not publish it and the ETL does not request it, so the shortest arc
is used: deterministic, and no less arbitrary than anything else given no data.
Planets with no published inclination default to face-on, which is the honest
reading of an unconstrained orbit rather than a guess at a tilt.

Unifying this replaced the direct eclipticToEquatorial call in the renderer, so
solar-system bodies and moons come out exactly where they did before — verified
against Sol side by side.

Tests: 253 passing, up from 247. The strongest one is the definition itself: a
90-degree planet must pass through our line of sight to the star, which is what
a transit is. One test of mine had to be corrected rather than the code — it
asserted that two systems at the same inclination must occupy different planes,
which is not guaranteed once the node angle is arbitrary, while each still sits
at the correct angle to its own host.

Note the e2e camera-flight test flaked once under parallel load during this
work, then passed in isolation and on two further full runs. Its click-until-
entered poll has a fixed 15s budget that a loaded machine can exceed; that is
pre-existing and unrelated to this change.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WaySiNst4HhDXBHnMy8p5G

README.md

@@ -52,11 +52,13 @@ same place an in-scene click would.
   star field is instanced quads on a `SpriteNodeMaterial` instead, which behaves the same on
   both backends. Their size is angular rather than world-space — real stars are unresolvable
   point sources, so apparent size should follow brightness, not distance.
-- **One reference frame.** The two data sources disagree: HYG gives star positions in
-  equatorial J2000, while JPL Horizons reports orbital elements against the ecliptic, tilted
-  23.4° away. The scene is equatorial throughout and orbits are rotated into it, so a direction
-  means the same thing in both views. Systems are still presented face-on — by placing the
-  camera relative to the orbital plane rather than by rotating the world into a convenient pose.
+- **One reference frame, from three sources.** HYG gives star positions in equatorial J2000.
+  JPL Horizons reports orbital elements against the ecliptic, tilted 23.4° away. The Exoplanet
+  Archive measures inclination from the *plane of the sky* — perpendicular to our line of sight
+  to each host star, which is why transiting planets cluster at 90°. Each set of elements is
+  rotated from its own reference plane into the scene's equatorial frame, so a direction means
+  the same thing everywhere. Systems are still presented face-on — by placing the camera
+  relative to the orbital plane rather than by rotating the world into a convenient pose.
 - **Two coordinate scales.** The galaxy view works in parsecs and the system view in AU —
   about eight orders of magnitude apart, which wrecks float precision if rendered in one unit
   space. The camera rig recentres the active star to the origin ("floating origin") and swaps