feat(lanes): add MIGRATIONS_DIR + GENERATED_MERGE_PATHS profile declarations (E2)

server/lib/lane-profile.js

@@ -76,6 +76,15 @@ const DEFAULTS = Object.freeze({
   // stack `ship-feature-lane`'s Stage 3 boots for QC. Empty = off, same as
   // every declaration above.
   QC_BOOT_ENV: "",
+  // E2: repo-relative path to a numbered-migrations directory (e.g.
+  // "db/migrations"), consumed by sync-base's collision preflight. Empty =
+  // off, same DEFAULTS pattern as every declaration above.
+  MIGRATIONS_DIR: "",
+  // E2: space-separated repo-relative paths given a keep-ours merge driver
+  // by sync-base's merge mode and regenerated post-merge by the profile's
+  // `regen` hook (e.g. an OpenAPI contract + its generated client). Empty =
+  // off — no driver installed, no regen fold-in attempted.
+  GENERATED_MERGE_PATHS: "",
 });
 
 /**
@@ -173,6 +182,7 @@ function resolveProfile(lane) {
       hooks,
       ports: splitList(env.PORTS),
       laneDirs: splitList(env.LANE_DIRS),
+      generatedMergePaths: splitList(env.GENERATED_MERGE_PATHS),
     };
   }
   return null;