docs: PRD rev1 re-review — repoint PRD heading anchors to GOV.4, complete archive line cites

Addresses CPS-PRD-REV1-REREVIEW findings on PR #1491 head 13968e9a:

F1 (blocker; the CI test failure): docs/PRD.md is now the permanent shim, so
heading-fragment links into the former PRD body no longer resolve —
fleet-documentation.spec.ts failed on docs/fleet/README.md's FCM anchor. The
Part II workstream contracts live in
docs/PRDs/2026-08-31_PRD_rev1/GOV.4-workstream-contracts.md; all five anchored
links in the tree are repointed there (fleet/README.md, TASKS.md,
release-integrity/TASKS.md, ADMIN-GUIDE mos-connector-lease-operations.md,
DEVELOPER-GUIDE mos-runtime-portability-m1.md). Each anchor verified against
the GOV.4 headings with the spec's slug rule. Bundle content unchanged.

F2 (minor): the rev0 archive README's ./ROADMAP.md row now cites all three
source lines (18, 177, 249).

docs/fleet/README.md

@@ -1,6 +1,6 @@
 # Fleet Configuration Management
 
-This book documents the local roster-v2 desired-state control plane delivered under issue #758. The normative requirements are the [FCM section of the repository PRD](../PRD.md#fleet-declarative-configuration-management-workstream-fcm-758), not the older fleet-suite or observability planning pages.
+This book documents the local roster-v2 desired-state control plane delivered under issue #758. The normative requirements are the [FCM section of the repository PRD](../PRDs/2026-08-31_PRD_rev1/GOV.4-workstream-contracts.md#fleet-declarative-configuration-management-workstream-fcm-758), not the older fleet-suite or observability planning pages.
 
 ## Authority boundary