fix(cli): include readonly flow-write warnings in os validate --json (#3465 follow-up) (#3480)

`validateReadonlyFlowWrites` warnings (the `readonlyWhen` advisory added in
#3465) were printed in human mode but left out of the `--json` summary's
`warnings` array, where every other advisory category is aggregated. So
`os validate --json` consumers (CI, editors) silently missed them. Add
`...readonlyWriteWarnings` to the summary array so JSON and human output agree.

Co-authored-by: Jack Zhuang <277994282+os-zhuang@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: os-zhuang

.changeset/readonly-flow-write-json-warning.md

@@ -0,0 +1,11 @@
+---
+"@objectstack/cli": patch
+---
+
+fix(cli): include readonly flow-write warnings in `os validate --json` output
+
+The `readonlyWhen` flow-write advisory (`validateReadonlyFlowWrites`, #3465) was
+printed in human mode but omitted from the `--json` summary's `warnings` array,
+where every other advisory category is aggregated. `os validate --json`
+consumers (CI, editors) therefore never saw those warnings. Added
+`...readonlyWriteWarnings` to the summary array so JSON and human output agree.

packages/cli/src/commands/validate.ts

@@ -562,7 +562,7 @@ export default class Validate extends Command {
           valid: true,
           manifest: config.manifest,
           stats,
-          warnings: [...exprWarnings, ...widgetWarnings, ...actionRefWarnings, ...styleWarnings, ...jsxWarnings, ...capWarnings, ...flowReadinessWarnings, ...flowTemplateWarnings, ...securityAdvisories, ...capProviderWarnings],
+          warnings: [...exprWarnings, ...widgetWarnings, ...actionRefWarnings, ...styleWarnings, ...jsxWarnings, ...capWarnings, ...flowReadinessWarnings, ...flowTemplateWarnings, ...readonlyWriteWarnings, ...securityAdvisories, ...capProviderWarnings],
           conversions: conversionNotices,
           specVersionGap: specGap,
           duration: timer.elapsed(),