fix(grpc): serialize Diagnostic.Detail across plugin boundary (closes #52, restores deploy-log visibility)

[intel352]

Summary

Closes the silent-drop bug that nullified PR-E2 (v0.8.3) + PR-E4 (v0.8.4) deploy-log fetch work. Also closes #52 (CHANGELOG duplicate ### Fixed heading).

Bug

`internal/module_instance.go::invokeDriverTroubleshoot` serialized `Diagnostic` to `map[string]any` but omitted the `detail` field. wfctl's `remoteResourceDriver.Troubleshoot` reads `m["detail"]` → empty → `emitDiagnostics` never printed Detail body. All work in `attachDeployLogs` to populate Diagnostic.Detail with deploy-log content + visible failure notes was silently dropped at the gRPC boundary.

Symptom (run 25261030300, post-PR-E5 with v0.8.4):

```
##[group]Troubleshoot: coredump-nats-staging
[deploy.components.coredump-nats-staging.wait] f066ea13 — Your deploy failed because your container exited with a non-zero exit code. (at 2026-05-02T20:25:29Z)
[CANCELED] 0059b12b — app spec updated (at 2026-05-02T20:25:26Z)
[deploy.components.coredump-nats-staging.wait] f42b2596 — Your deploy failed because your container exited with a non-zero exit code. (at 2026-05-02T19:36:50Z)
##[endgroup]
```

Cause line ✓ but no Detail block, no log content, no failure-mode notes — exactly what we'd been working to surface for the past 4 plugin releases.

Fix

One-line addition to the diagnostics list-builder:
```go
diagList[i] = map[string]any{
"id": d.ID,
"phase": d.Phase,
"cause": d.Cause,
"at": d.At.Format(time.RFC3339),
"detail": d.Detail, // NEW
}
```

Plus regression test (`TestGRPCDispatch_ResourceDriver_Troubleshoot_Detail_RoundTripFidelity`) that exercises the full grpcRoundTrip → InvokeMethod → response path with a fakeTroubleshootingDriver producing a Diagnostic with Detail set, and asserts the field survives intact.

CHANGELOG dedup (closes #52)

Removed the duplicate `### Fixed` heading PR-E4 introduced. Now exactly one `### Added` and one `### Fixed` under [Unreleased].

Test plan

• go test ./internal/... -count=1 (full suite green)
• New regression test passes
• Validates against next core-dump staging deploy (will surface actual container stdout/stderr OR a clear visible-failure note in Diagnostic.Detail)

Why this is a structpb-boundary class bug

Per workspace memory `feedback_workflow_plugin_structpb_boundary` — domain types crossing the gRPC plugin boundary need every field enumerated in the dispatch translator. Diagnostic.Detail wasn't a typed slice but the same pattern (translator forgets a field → silently drops at boundary). Adding a similar regression test for every field of every domain type that crosses the boundary would catch this whole class of bug.

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

[Copilot]

Pull request overview

This PR fixes a gRPC dispatch bug in the plugin layer where Diagnostic.Detail was not being serialized out of ResourceDriver.Troubleshoot, which prevented deploy/build log details from reaching wfctl. It also adds a regression test around the dispatch path and cleans up the unreleased changelog entry structure.

Changes:

• Add detail to the serialized troubleshooting diagnostic map in invokeDriverTroubleshoot.
• Add a regression test covering troubleshooting diagnostic detail through the dispatch boundary.
• Consolidate the duplicate ### Fixed heading in CHANGELOG.md and document the bug fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
internal/module_instance.go	Fixes troubleshooting diagnostic serialization so Detail crosses the plugin boundary.
internal/grpc_dispatch_test.go	Adds regression coverage for ResourceDriver.Troubleshoot diagnostic detail dispatch behavior.
CHANGELOG.md	Merges duplicate unreleased Fixed sections and records the serialization fix.

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