Decode tfrag normals from the overlay's sine table

Normals are per-vertex, and the tfrag's light records store them as an
azimuth and elevation *index* into a 256-entry sine table rather than as
angles. This decodes that table and builds normals for the renderer.

The reference reads the table from an ELF at BOOT_NORMAL_TABLE_VADDR
(0x165500) and notes every level overlay carries a copy. The overlay has
no ELF header -- it is a raw loadable image starting with code -- so there
is no program header to map a virtual address through, and the offset is
not fixed either: level 0 has the table at 0xb650c, level 5 at 0xcca30,
level 26 at 0xb6284.

So it is located by content. Every table starts with exactly (1.0, 0.0),
angle zero, and the scan then requires all 256 entries to match
cos(i*pi/128), sin(i*pi/128). Validating the whole curve is what makes the
search safe: a lone (1.0, 0.0) pair of floats occurs by accident in a
2.7 MB executable, and a test plants one as a decoy. The values are read
from the disc rather than recomputed, since those are the numbers the game
indexes.

A normal is (cos(az)cos(el), sin(az)cos(el), sin(el)) *negated* -- the
stored normals point into the surface -- and then given the same Z-up to
Y-up swap as positions, or the lighting comes out sideways. The azimuth
and elevation fields are stored signed but index 0..=255, so entry 200
must be read as 200, not as -56; there is a test for that.

Also frames and parses the level light bank from the gameplay extent, and
the pipeline now writes overlay.bin. The per-vertex lighting evaluation
is not written yet, so the renderer stays unlit by default. GC_ENGINE_LIT=1
substitutes a host directional light for inspection -- that is a stand-in,
not the game's lighting, and it is deliberately not the default.

The hash table is regenerated for the 27 new overlay.bin files: now 5,213
files and 5,762,497,559 bytes.

crates/gc-formats/src/tfrag.rs

@@ -611,13 +611,26 @@ pub struct TfragRgba {
 pub struct TfragLight {
     pub unknown_0: i8,
     pub intensity: i8,
-    /// Normal azimuth, pi/128 radians per unit.
+    /// Normal azimuth, as an *index* into the overlay's 256-entry sine table.
     pub azimuth: i8,
-    /// Normal elevation, pi/128 radians per unit.
+    /// Normal elevation, as an index into the same table.
     pub elevation: i8,
     pub color: i16,
 }
 
+impl TfragLight {
+    /// Azimuth as the unsigned table index. The field is stored signed but
+    /// indexes 0..=255, so the byte is what matters, not its sign.
+    pub fn azimuth_index(&self) -> u8 {
+        self.azimuth as u8
+    }
+
+    /// Elevation as the unsigned table index.
+    pub fn elevation_index(&self) -> u8 {
+        self.elevation as u8
+    }
+}
+
 /// Everything one tfrag contributes to a draw call.
 #[derive(Debug, Clone, Default, PartialEq)]
 pub struct TfragGeometry {