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.

enterprise/enterprise.yaml

@@ -6,6 +6,9 @@ enterprise:
   description: >-
     Enterprise index for the Valsts Kase / Vienotais pakalpojumu centrs (VPC)
     accounting workspace — a UAPF transcription of the six published accounting
-    function groups (FG1–FG6). Domain and process packages are registered here
-    as they are added to the workspace.
-packages: []
+    function groups (FG1-FG6).
+packages:
+  - ref: ../domains/gramatvediba
+    level: 1
+    domain: gramatvediba
+    tags: [accounting, valsts-kase, vpc]