commit-msg.txt

feat(cli): add investigate and export-summary commands (#488)

Brings the investigation-memory workflow to the CLI (issue #488).

## New commands

### investigate
- Calls `IInvestigationPlanner.Plan()` (Core-only, no I/O) with the target pid
  (auto-resolved when omitted), optional `--symptom`, `--hypothesis`, and
  `--max-tool-calls` constraints.
- Routes cold / warm / hypothesis mode exactly as the MCP `start_investigation`
  tool does, using the same `InvestigationRequest` + `InvestigationConstraints`
  value objects from Core.
- Renders the next recommended step (tool name + rationale), the full step list,
  and early-stop conditions in human-readable form; `--json` emits the full
  `DiagnosticResult<InvestigationPlan>` envelope.

### export-summary
- Reads a `CpuSampleTraceArtifact` from the session handle store via
  `IInvestigationSummaryExporter.Export()` (Core-only).
- Requires `--handle <id>` (a CPU-sample handle from `collect --kind cpu` in a
  `session` REPL — handles are session-scoped).
- Streams the portable summary JSON to stdout or writes to `--out <file>`.
- Server is stateless: the caller owns persistence (paste JSON into a PR / ADR).

## Changes

- **CliOptions**: `--symptom`, `--hypothesis`, `--max-tool-calls`, `--top-hotspots`
- **CliCommands**: Commands list, `RunAsync` routing, `TryValidateInvestigate`,
  `TryValidateExportSummary`, `InvestigateAsync`, `ExportSummaryAsync`
- **CliHelp**: focused help entries for both commands
- **CliCompletionScripts**: `CommandOptions` entries + `ValueFlags` additions
- **CliHintProjection**: `start_investigation` → `investigate`,
  `export_investigation_summary` → `export-summary` mappings in `ToolToCommand`
  and `ReasonRewrites` (so Core hints using MCP names project cleanly to CLI vocab)
- **Tests**: 18 new parse / validation tests in `CliInvestigateTests.cs`

All 327 CLI tests pass. Full solution builds with zero warnings in source projects.

Closes #488

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>