[BUG] New custom NPC starts at relationship delta 2.0 instead of the configured delta #375

Summary

A custom NPC that is new to an existing save starts at the vanilla relationship delta 2.0 instead of the delta set with NPCRelationshipDataBuilder.WithDelta. The configured delta arrives a few seconds later, when the deferred FinalizeNetworkSpawn applies the relationship defaults. Code that reads the relationship in that window (customer setup, mod UI, a console dump right after load) gets 2.0.

Environment

• Schedule I 0.4.7f12, IL2CPP, MelonLoader 0.7.3. The code path is shared with Mono.
• S1API 3.2.1, and stable at c9ac103.

Steps to reproduce

1. Register a physical customer NPC with WithRelationshipDefaults(r => r.WithDelta(2.5f)), for example a Personnel pack NPC with "relationships": { "delta": 2.5 }.
2. Load an existing save that has never seen this NPC.
3. Read npc.RelationData.RelationDelta as soon as the save is loaded.

Expected behavior

2.5 from the first read.

Observed behavior

• Read at load: relDelta=2 unlockType=Recommendation.
• Same NPC a few seconds later: relDelta=2.5.

Not the same as #260 (saved values lost on reload). This is the starting value before any save exists.

Cause

NPCRelationData.Init sets RelationDelta = NPCData.Relationship.DefaultRelationshipValue * 5. S1API leaves DefaultRelationshipValue at the vanilla 0.4 and applies the configured delta only in FinalizeNetworkSpawn, which NPCNetworkBootstrap defers. Init runs twice before that:

1. In the S1API constructor (InitializeRelationshipData).
2. In native Awake of the spawned instance.

Both start the NPC at 2.0.

Suggested fix

Write delta / 5 into Relationship.DefaultRelationshipValue before both Init calls. Saved relationship data still replaces it during load.