KTD1 fifth step (behavior preserved):
- squad.AssetProvider{DocTemplate,RenderDoc,AgentInstruction,
AgentInstructionFile} injected via Options.Assets into Service,
WorkspaceEngine and AdaptivePlanner
- bizdev templateAssetProvider maps port to internal/template (assembly side)
- nil-provider paths degrade to the same fallbacks the old error branches
used (placeholder template, role header) — fail-visible, no guessing
- squad -> template import eliminated; arch edge moved bizdev->template
- verified: build/vet/arch green, squad+bizdev short tests pass