game_data: typed loaders for the combat / character / mission tables

Decode Project Sylpheed's IDXD data model into plain, cloneable structs
(from GP_MAIN_GAME_E.pak; the D/F/I/J/S paks are localized dups):

- Weapon (121), CraftUnit (89, with the AI flight model in .fields),
  Vessel (23, structural component counts), PlayerConfig (24) — the
  full combat balance.
- Character (68 — faction + portrait set), Stage (29 missions:
  location, phases, and the per-stage resource tables it wires up).
- Generic Record / load_records(schema) reads any of the 105 IDXD
  schemas without a bespoke struct.

Each blob = one entity; token[0] names the table, fields are
value-before-key. Named Option<> fields for the common stats + a full
`fields` map; defaulted fields stay None (they're code-resident, not on
disc — honest blanks, never guessed). 8 tests against the real disc.

Examples: iso_map / deep_map census the ISO's formats and IDXD schemas;
dm_extract / dm_rows / dm_roster / mission_map dump the decoded data.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/sylpheed-formats/examples/spawn_survey.rs

@@ -0,0 +1,33 @@
+use sylpheed_formats::{idxd::IdxdObject, PakArchive};
+use std::collections::BTreeMap;
+fn main(){
+    let disc=std::env::var("SYLPHEED_DISC").unwrap();
+    let arc=PakArchive::open(format!("{disc}/dat/GP_MAIN_GAME_E.pak")).unwrap();
+    // schemas whose type0/content is squadron/formation/route/group/position
+    let mut hit:BTreeMap<u32,(u32,String,String)>=BTreeMap::new();
+    for e in arc.entries(){
+        let Ok(b)=arc.read(e) else{continue}; let Ok(o)=IdxdObject::parse(&b) else{continue};
+        let t=o.tokens(); let t0=t.first().cloned().unwrap_or_default();
+        let joined:String=t.iter().take(20).map(|s|s.as_str()).collect::<Vec<_>>().join(" ");
+        if ["Squadron","Formation","Route","UnitGroup","Position","Spawn","Wave","Frame","NullFrame"].iter().any(|k|t0.contains(k)||joined.contains(k)){
+            let ent=hit.entry(o.schema_hash).or_insert((0,t0.clone(),joined.chars().take(90).collect()));
+            ent.0+=1;
+        }
+    }
+    let mut v:Vec<_>=hit.into_iter().collect(); v.sort_by_key(|x|std::cmp::Reverse(x.1.0));
+    for (s,(c,t0,sample)) in &v{ println!("[{s:08x}] ×{c:<4} type0={t0:<18.18} :: {sample}"); }
+    // dump a Squadron/UnitGroup blob fully to see if it has positions (binary floats) or refs
+    println!("\n─── sample squadron/formation blob (first matching) ───");
+    for e in arc.entries(){
+        let Ok(b)=arc.read(e) else{continue}; let Ok(o)=IdxdObject::parse(&b) else{continue};
+        let t=o.tokens(); let t0=t.first().cloned().unwrap_or_default();
+        if t0.contains("Squadron")||t0.contains("Formation")||t0.contains("UnitGroup"){
+            println!("schema {:08x} type0={t0} count={} tokens={}, blob {}B", o.schema_hash,o.count,t.len(),b.len());
+            for (i,tk) in t.iter().take(30).enumerate(){ print!("{i:>2}:{tk:<20.20}"); if i%4==3{println!();} } println!();
+            // scan blob for float-like values (reasonable coords) in the binary region
+            let nfloats=(0..b.len().saturating_sub(4)).step_by(4).filter(|&i|{let f=f32::from_be_bytes([b[i],b[i+1],b[i+2],b[i+3]]); f.is_finite()&&f.abs()>1.0&&f.abs()<1e6}).count();
+            println!("  ~{nfloats} plausible BE-float words in blob (positions live in binary region if high)");
+            break;
+        }
+    }
+}