composition skeleton: L1 accounting domain + six L2 function-group packages

Step 2 of the vk-gramatvediba build (absorbs the planned Step 3 — the
enterprise index now references the domain, since the two are one
coherent unit).

- domains/gramatvediba/ — L1 domain package; includes the six FG packages
- processes/fg1..fg6/ — six L2 function-group packages (composition stubs;
  FG3 carries its sub-process inventory and is taken to executable depth
  in later steps)
- each package: uapf.yaml + metadata/ownership.yaml + metadata/lifecycle.yaml
  + README
- enterprise/enterprise.yaml now references the L1 domain

All 22 manifests and metadata files validate against the UAPF 2.2.0
schemas; all seven includes / enterprise references resolve.

processes/fg3/metadata/ownership.yaml

@@ -0,0 +1,8 @@
+kind: uapf.metadata.ownership
+owners:
+  - type: organization
+    id: vpc
+    name: Vienotais pakalpojumu centrs (Valsts Kase)
+    role: owner
+approvers:
+  - vpc.process-office