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

src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Management/InstanceCommands.cs

@@ -62,3 +62,26 @@ public record DeleteInstanceNativeAlarmSourceOverrideCommand(
     string SourceCanonicalName);
 
 public record ListInstanceNativeAlarmSourceOverridesCommand(int InstanceId);
+
+/// <summary>
+/// One entry in a bulk native-alarm-source-override apply: the source binding's
+/// canonical name plus the three optional retarget fields (null keeps the inherited
+/// value). Mirrors <see cref="SetInstanceNativeAlarmSourceOverrideCommand"/>'s fields
+/// for a single source.
+/// </summary>
+public record NativeAlarmSourceOverrideEntry(
+    string SourceCanonicalName,
+    string? ConnectionNameOverride,
+    string? SourceReferenceOverride,
+    string? ConditionFilterOverride);
+
+/// <summary>
+/// Bulk, all-or-nothing apply of per-instance native-alarm-source overrides — the
+/// native-source parity analogue of <see cref="SetInstanceOverridesCommand"/>. Backs
+/// the CLI <c>instance native-alarm-source import --file</c> CSV path. Every entry's
+/// source must resolve for the instance and be unlocked; if any entry is invalid the
+/// whole batch is rejected before any write.
+/// </summary>
+public record SetInstanceNativeAlarmSourceOverridesCommand(
+    int InstanceId,
+    IReadOnlyList<NativeAlarmSourceOverrideEntry> Overrides);