fix(siteruntime): self-healed and newly-enabled instances now get their DCL connections (register row 85)

An Instance Actor started by a self-heal came up with NO DCL connection actors,
so every tag it subscribed was answered "Unknown connection: <name>" by the DCL
manager indefinitely. Proven live 2026-08-16 by the row-78 close-out probe: the
sweep correctly started the replication-seeded instances, then every subscribe
failed for 6+ min until a second pair restart.

Root cause is narrower than the register assumed. A DCL connection actor is
never created from data_connection_definitions -- that table has no production
reader at all (GetAllDataConnectionDefinitionsAsync is called only by a test).
It exists only as a side effect of starting an instance, from the Connections
map inside that instance's own flattened config, via EnsureDclConnections.

That ensure was the CALLER's job and only two of the four callers made it:

  CreateInstanceActorBatch (boot)   ensured  OK
  ApplyDeployment (deploy)          ensured  OK
  StartStoredInstance               MISSING  <- row-67 ensure-started + row-78 sweep
  HandleEnableResult                MISSING  <- enabling a disabled instance

The two misses are the two paths added after the original pair -- the signature
of a convention living at call sites instead of in the funnel.

It was never replication-specific: the boot load reads only ENABLED configs, so
a node booting with an instance disabled never creates its connections either,
and enabling it afterwards hit the identical dead end on an ordinary
unreplicated site.

Fix: EnsureDclConnections moves into CreateInstanceActor, already documented as
the single Instance Actor creation funnel (it is where the running revision is
stamped for the same reason), and the two caller-side calls are removed. Placed
before the already-exists guard so the two paths that already called it keep
their exact previous semantics. No new message, option or DCL change -- it
reuses EnsureDclConnection's existing per-name hash guard, so steady state is
silent. Structural rather than another guard: a fifth start path cannot forget.

Deliberately NOT done, with rationale in the memo: a sweep pass over
data_connection_definitions. It would not have fixed row 85 (that table is empty
on a site that has only ever received instance deploys), and re-hashing from it
would fight the deploy path over the same per-name hash slot, recreating
connection actors and dropping live subscriptions on a loop. Two residual
sibling gaps (connection-only artifact deploy replicating to a peer that never
adopts it, and the mirror-image removal case) are recorded in the memo and the
component docs as open, not silently skipped.

Tests: SelfHealCreatesDclConnectionTests, 7 tests asserting on the
CreateConnectionCommand messages sent to a recording DCL stand-in. Verified
fail-before against a behavioral revert (call removed from the funnel, restored
at the two original sites): 4 fail / 3 pass, the 3 being steady-state silence
plus two refactor guards that must pass on both sides.

Docs: sweep design memo gains section 7; Component-SiteRuntime,
Component-DataConnectionLayer, docs/components/SiteRuntime and
docs/components/DataConnectionLayer updated (the deploy-flow step ordering in
docs/components/SiteRuntime was stale as written).

docs/components/SiteRuntime.md

@@ -36,6 +36,8 @@ The staggered startup above reads storage exactly once. Anything that writes a `
 
 `DeploymentManagerActor` therefore runs a periodic sweep (`InstanceSweepIntervalSeconds`, default 60; `0` disables) that re-reads the durable rows off-thread and, on the actor thread, for every **enabled** stored config either starts a missing `InstanceActor` or — when the running one's revision no longer matches the stored one — re-applies the stored config **through the ordinary redeploy path**, so nothing about redeploy semantics is re-implemented. It defers to any in-flight deploy/warm/termination, never starts a disabled instance, stays inert until boot-time creation has finished, makes one repair attempt per (instance, revision) pair so it can never become a restart loop, and is completely silent when there is nothing to repair. Repairs emit Warning `deployment` site events naming the trigger (and, for a stale-revision restart, both revisions). Design note: `docs/plans/2026-08-15-instance-sweep-self-heal-design.md`.
 
+Register row **85** was the same gap one layer down: the sweep started the instance, but the instance came up with **no DCL connection actors**, so every tag subscribe was answered `Unknown connection: <name>`. The connection push (`EnsureDclConnections`) was the *caller's* job and two of the four Instance-Actor start paths omitted it; it now lives inside `CreateInstanceActor`. See *Deployment flow* below and §7 of the design note.
+
 ### Actor supervision and lifetimes
 
 | Actor | Kind | Supervises children with | On exception |
@@ -83,10 +85,11 @@ Prior to WP3.1 (2026-08-15) each invocation spawned a short-lived `ScriptExecuti
 
 Central sends a `DeployInstanceCommand` carrying a JSON `FlattenedConfiguration` to the site singleton. The singleton:
 
-1. Calls `EnsureDclConnections` to push any new or changed connection definitions to the DCL manager (hash-guarded: unchanged configs are skipped).
-2. Calls `CreateInstanceActor`, which does `Context.ActorOf(props, instanceName)`.
-3. Runs an off-thread `Task` that calls `SiteStorageService.StoreDeployedConfigAsync` and clears static overrides and native alarm state. Nothing is pushed to the peer: as of LocalDb Phase 2 those three tables are replicated, so the writes themselves reach the standby.
-4. Pipes back a `DeployPersistenceResult`; only on success does it tell the deployer `DeploymentStatus.Success`. If persistence fails, the optimistically-created actor is stopped and the error is returned to central (`SiteRuntime-005`).
+1. Calls `CreateInstanceActor`, which first calls `EnsureDclConnections` to push any new or changed connection definitions to the DCL manager (hash-guarded: unchanged configs are skipped), then does `Context.ActorOf(props, instanceName)`.
+2. Runs an off-thread `Task` that calls `SiteStorageService.StoreDeployedConfigAsync` and clears static overrides and native alarm state. Nothing is pushed to the peer: as of LocalDb Phase 2 those three tables are replicated, so the writes themselves reach the standby.
+3. Pipes back a `DeployPersistenceResult`; only on success does it tell the deployer `DeploymentStatus.Success`. If persistence fails, the optimistically-created actor is stopped and the error is returned to central (`SiteRuntime-005`).
+
+> **`CreateInstanceActor` is the single funnel for the connection push too (register row 85)**: the `EnsureDclConnections` call moved *into* `CreateInstanceActor` on 2026-08-17. It used to sit at each caller, and only two of the four callers made it — the boot-time batch and this deploy path. `StartStoredInstance` (row-67 ensure-started and the row-78 sweep) and `HandleEnableResult` did not, so a self-healed or newly-enabled instance came up with no connection actors and every tag subscribe was answered `Unknown connection: <name>` indefinitely. See the *Instance reconcile sweep* section and `docs/plans/2026-08-15-instance-sweep-self-heal-design.md` §7.
 
 For redeployment (instance already running), the existing actor is stopped and watched: