re(route-b): 13 defaulted Size_Y values read out of the running game

Live definition objects carry no name, so identity comes from the values:
unit_signatures.rs prints (HP, Size_X/Y/Z) for every disc unit and vessel, and a
live object is the record whose known fields it reproduces. 7 of 14 match a disc
record outright; the other 7 match nothing because their records default a field
-- 18 of 23 vessel records are missing at least one, nearly always Size_Y.

Matching each single-default record against the live object that reproduces its
remaining fields resolves 13 values (Destroyer 200, Cruiser 600/700, ASFrigate
80, ADAN Destroyer 300, Acropolis 400, ISCMissile 300, plus _Inv/_EX variants).
Every one equals that unit's Size_X, so the engine's own parsed definitions
confirm the statically-derived inheritance rule.

Limits stated: variants share one live object, and the ...Ratio/...Count family
is not resolved -- their offsets in the live object are still unknown.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/sylpheed-formats/examples/unit_signatures.rs

@@ -0,0 +1,33 @@
+//! (HP, Size_X, Size_Y, Size_Z) for every craft unit and vessel on the disc.
+//!
+//! A live definition object in guest RAM carries HP at `+0x54` and the sizes at
+//! `+0x30/34/38` but no name in its first words, so identity has to come from the
+//! values themselves: this is the lookup table for that match.
+//! Run: unit_signatures <disc-root>
+use sylpheed_formats::game_data::{load_units, load_vessels};
+use sylpheed_formats::PakArchive;
+fn main() {
+    let disc = std::env::args().nth(1).expect("disc root");
+    let pak = PakArchive::open(format!("{disc}/dat/GP_MAIN_GAME_E.pak")).expect("pak");
+    println!("{:<34} {:>9} {:>8} {:>8} {:>8}  kind", "id", "hp", "size_x", "size_y", "size_z");
+    for u in load_units(&pak) {
+        println!(
+            "{:<34} {:>9} {:>8} {:>8} {:>8}  unit",
+            u.id.unwrap_or_default(),
+            u.hp.map(|v| v.to_string()).unwrap_or("—".into()),
+            u.size_x.map(|v| v.to_string()).unwrap_or("—".into()),
+            u.size_y.map(|v| v.to_string()).unwrap_or("—".into()),
+            u.size_z.map(|v| v.to_string()).unwrap_or("—".into()),
+        );
+    }
+    for v in load_vessels(&pak) {
+        println!(
+            "{:<34} {:>9} {:>8} {:>8} {:>8}  vessel",
+            v.id.unwrap_or_default(),
+            v.hp.map(|x| x.to_string()).unwrap_or("—".into()),
+            v.size_x.map(|x| x.to_string()).unwrap_or("—".into()),
+            v.size_y.map(|x| x.to_string()).unwrap_or("—".into()),
+            v.size_z.map(|x| x.to_string()).unwrap_or("—".into()),
+        );
+    }
+}