formats: ship module — reconstruct capital ships from XBG7 part families

Project Sylpheed never stores a capital ship as a single mesh. Each ship is
modelled, then split into destructible parts (hull segments, bridge, engines,
integral turrets), each shipped as its own XBG7 resource inside a
hidden/resource3d/Stage_SNN.xpr container. The split lets the game hide/replace
a part when the player destroys it. Crucially each part keeps its ship-local
position, so reconstructing the whole ship is: draw every base part of one id
together, untransformed.

New `ship` module: Faction (from the e/f/n id prefix — ADAN/TCAF/Neutral),
ShipModel, ship_id_of, is_base_part (skips _l/_m/_d LODs, _bNN/_dead/_break
destruction geometry, e_rou_ scene nodes), and ships_in_container to group a
stage's resources into whole ships.

Supporting:
- mesh::xbg7_resource_names — list a container's XBG7 resource names (directory
  walk only, no geometry decode).
- Xbg7Model::models_named — decode only the named resources (assemble a ship
  from its ~8 parts instead of the whole ~300-resource stage).
- game_data::Vessel gains `model` (the rou_<id> hull stem) to link stats to the
  3D part family.

Tests: id/part classification + a disc-gated reconstruction of the ADAN e108
frigate from Stage_S02.

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

crates/sylpheed-formats/src/game_data.rs

@@ -224,6 +224,9 @@ pub fn load_units(pak: &PakArchive) -> Vec<CraftUnit> {
 pub struct Vessel {
     pub id: Option<String>,
     pub name: Option<String>,
+    /// The 3D hull resource stem, e.g. `rou_e105` — the `eNNN`/`fNNN` id links to
+    /// the XBG7 part family (`e105_bdy_*`, `e105_brg_*`, …) inside a `Stage_SNN.xpr`.
+    pub model: Option<String>,
     pub hp: Option<f32>,
     pub size_x: Option<f32>,
     pub size_y: Option<f32>,
@@ -247,6 +250,7 @@ impl Vessel {
         Some(Vessel {
             id: o.get_raw("ID").map(str::to_string),
             name: o.get_raw("Name").map(str::to_string),
+            model: o.get_raw("Model").map(str::to_string),
             hp: as_f32(f.get("HP")),
             size_x: as_f32(f.get("Size_X")),
             size_y: as_f32(f.get("Size_Y")),