feat(instance): native-alarm-source-override CSV bulk import (deferred #12) + doc fixes

Closes the operator parity gap the deferred-work register tracked as #12: native
alarm source overrides could only be set one-at-a-time, while attribute overrides
had a CSV bulk path. Adds an all-or-nothing CSV import for native sources.

- Commons: extract the RFC-4180 line splitter into a shared CsvLineSplitter
  (refactor OverrideCsvParser onto it — no behavior change, pinned by its tests);
  new NativeAlarmSourceOverrideCsvParser (header SourceName,Connection,
  SourceReference,Filter; blank = inherited).
- Commons: NativeAlarmSourceOverrideEntry + bulk SetInstanceNativeAlarmSource-
  OverridesCommand (auto-registered via the reflection command registry).
- ManagementService: Deployer-gated handler — flattens once, validates every
  source resolves + is unlocked + no duplicates up front, then upserts the whole
  batch under a single SaveChanges (true all-or-nothing txn). Added to the frozen
  authorization matrix; dispatch-coverage guard passes.
- CLI: `instance native-alarm-source import --instance-id --file` (parity with
  `instance import-overrides`) + README.
- Tests: native parser (Commons), CLI parse/entry mapping, 3 bulk-handler tests
  (happy path single-commit, locked-source reject, unresolved-source reject).

Also corrects a stale XML-doc line in ScriptRuntimeContext (WaitForAttribute
quality-gated mode is shipped, not "planned") and updates the deferred-work
register: marks #7/#13/#15/#16/#20 verified-resolved, #12 as CLI/API-shipped with
only the Central UI upload affordance still pending.

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

tests/ZB.MOM.WW.ScadaBridge.ManagementService.Tests/RequiredRoleMatrixTests.cs

@@ -124,6 +124,7 @@ public class RequiredRoleMatrixTests
         ["SetInstanceAlarmOverride"] = [Roles.Deployer],
         ["DeleteInstanceAlarmOverride"] = [Roles.Deployer],
         ["SetInstanceNativeAlarmSourceOverride"] = [Roles.Deployer],
+        ["SetInstanceNativeAlarmSourceOverrides"] = [Roles.Deployer],
         ["DeleteInstanceNativeAlarmSourceOverride"] = [Roles.Deployer],
         ["GetDeploymentDiff"] = [Roles.Deployer],
         ["MgmtDeployArtifacts"] = [Roles.Deployer],