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.CLI/README.md

@@ -503,6 +503,31 @@ Clear an instance's native alarm source override, reverting to the inherited bin
 scadabridge --url <url> instance native-alarm-source clear --instance-id <int> --source <string>
 ```
 
+#### `instance native-alarm-source import`
+
+Bulk-apply native alarm source overrides for a single instance from a CSV file
+(all-or-nothing — the native-source parity of `instance import-overrides`). The CSV
+header is required: `SourceName,Connection,SourceReference,Filter`; a blank override
+field keeps the inherited value. Every named source must resolve for the instance and
+be unlocked, or the whole batch is rejected before any write.
+
+```sh
+scadabridge --url <url> instance native-alarm-source import --instance-id <int> --file <path>
+```
+
+| Option | Required | Description |
+|--------|----------|-------------|
+| `--instance-id` | yes | Instance ID |
+| `--file` | yes | Path to the override CSV (`SourceName,Connection,SourceReference,Filter`; blank field = inherited) |
+
+Example CSV:
+
+```csv
+SourceName,Connection,SourceReference,Filter
+Pressure,OpcB,ns=2;s=Pump.Alarm,Active
+Module.Temp,,,
+```
+
 #### `instance deploy`
 
 Deploy an instance to its site. Acquires the per-instance operation lock.