feat: add factionType filter to units query

Allows filtering units by faction classification (GREAT_HOUSE, CLAN,
PERIPHERY, etc.) via unit_availability join, so roster builders can
request e.g. "all mechs available to any Great House faction" without
specifying each faction individually.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: graylikeme

crates/api/src/db/units.rs

@@ -49,6 +49,7 @@ pub struct UnitFilter<'a> {
     pub bv_min: Option<i32>,
     pub bv_max: Option<i32>,
     pub faction_slug: Option<&'a str>,
+    pub faction_type: Option<&'a str>,
     pub era_slug: Option<&'a str>,
     pub is_omnimech: Option<bool>,
     pub config: Option<&'a str>,
@@ -130,6 +131,14 @@ pub async fn search(
         builder.push_bind(faction);
         builder.push(")");
     }
+    if let Some(ft) = filter.faction_type {
+        builder.push(r#" AND EXISTS (
+            SELECT 1 FROM unit_availability ua
+            JOIN factions f2 ON f2.id = ua.faction_id
+            WHERE ua.unit_id = u.id AND f2.faction_type = "#);
+        builder.push_bind(ft);
+        builder.push(")");
+    }
     if let Some(era) = filter.era_slug {
         builder.push(r#" AND EXISTS (
             SELECT 1 FROM unit_availability ua
@@ -364,6 +373,7 @@ mod tests {
             bv_min: None,
             bv_max: None,
             faction_slug: None,
+            faction_type: None,
             era_slug: None,
             is_omnimech: None,
             config: None,

crates/api/src/graphql/query.rs

@@ -148,6 +148,7 @@ impl QueryRoot {
         #[graphql(desc = "Minimum Battle Value filter (inclusive).")] bv_min: Option<i32>,
         #[graphql(desc = "Maximum Battle Value filter (inclusive).")] bv_max: Option<i32>,
         #[graphql(desc = "Filter to units available to this faction. Lowercase, hyphen-separated slug (e.g. \"clan-wolf\").")] faction_slug: Option<String>,
+        #[graphql(desc = "Filter to units available to any faction of this type.")] faction_type: Option<FactionTypeFilter>,
         #[graphql(desc = "Filter to units available in this era.")] era_slug: Option<EraFilter>,
         #[graphql(desc = "Filter to OmniMechs only (true) or non-OmniMechs (false).")] is_omnimech: Option<bool>,
         #[graphql(desc = "Filter by chassis config. One of: Biped, Quad, Tripod, LAM.")] config: Option<String>,
@@ -169,6 +170,7 @@ impl QueryRoot {
             bv_min,
             bv_max,
             faction_slug: faction_slug.as_deref(),
+            faction_type: faction_type.map(|f| f.as_db_str()),
             era_slug: era_slug.map(|e| e.as_db_str()),
             is_omnimech,
             config: config.as_deref(),