fix: set version in ActivateDataSet call and persist clearing account config (#1253)

* fix: wire deposit/withdrawal saga orchestration in unified binary

The unified binary's wireCurrentAccount used the basic NewService()
constructor which creates a Service without deposit/withdrawal
orchestrators, causing nil pointer panics on ExecuteDeposit calls.

Switch to NewServiceWithExistingClients() with loopback gRPC clients
for position-keeping and financial-accounting, enabling full Starlark
saga orchestration within the unified binary.

Also:
- Copy saga script assets into Docker image (SAGA_ASSET_DIR=/app)
- Fix init-databases.sql: meridian_internal_account → meridian_internal_bank_account

* fix: load clearing account config from env for deposit double-entry

Without a clearing account, the deposit saga only creates a CREDIT
posting (to customer). FA rejects the unbalanced booking log. Load
AccountConfig from DEPOSIT_CLEARING_ACCOUNT_ID env var so the saga
creates both DEBIT (clearing) and CREDIT (customer) postings.

Gracefully falls back to nil when env var is unset.

* fix: fail fast on invalid clearing account config

Differentiate "env var not set" (graceful skip) from "env var set but
invalid" (hard error) to avoid silently falling back to single-sided
postings when config is misconfigured.

* fix: use account_id for PK position logs in deposit and withdrawal sagas

The Starlark deposit and withdrawal scripts were passing
external_identifier (e.g. VE-GBP-010) as the position_id to
position_keeping.initiate_log, but the post-deposit balance query
uses account_id (e.g. ACC-xxx). This mismatch caused PK balance
lookups to fail with "no position logs found for account".

* fix: add required CEL expressions to seed-demo dataset registration

RegisterDataSet now requires validation_expression and
resolution_key_expression fields. Add appropriate CEL expressions
for the wholesale energy price dataset.

* fix: activate dataset before recording observations and persist clearing account config

- seed-demo: call ActivateDataSet after RegisterDataSet to transition
  from DRAFT to ACTIVE before recording observations
- docker-compose: add DEPOSIT_CLEARING_ACCOUNT_ID env var passthrough
  so it persists across deployments
- .env.demo.example: document the clearing account config

---------

Co-authored-by: Ben Coombs <bjcoombs@users.noreply.github.com>

Author: bjcoombs

cmd/seed-demo/main.go

@@ -473,7 +473,8 @@ func seedMarketData(ctx context.Context, conn *grpc.ClientConn) error {
 
 	// Activate dataset so observations can be recorded
 	_, err = client.ActivateDataSet(ctx, &marketv1.ActivateDataSetRequest{
-		Code: "WHOLESALE_ENERGY_GBP_KWH",
+		Code:    "WHOLESALE_ENERGY_GBP_KWH",
+		Version: 1,
 	})
 	if err == nil {
 		fmt.Println("  Activated dataset: WHOLESALE_ENERGY_GBP_KWH")