feat: in-app Orchestrator (Phase 2) — multi-agent conductor

Brings the deterministic Han-flow conductor into BooCode: launch any read-only
flow from BooChat or BooCoder, watch each agent stream live in a Paseo-style
run pane, get an evidence-disciplined report — on local Qwen, persisted and
resumable. Read-only enforced hard via qwen --approval-mode plan (orchestrator
tasks fail closed if qwen is unavailable; never fall to write-capable native).

Backend (apps/coder): re-homed conductor defs, flow_runs/flow_steps schema,
flow-runner + dispatcher onTaskTerminal hook, restart-resume, runs routes
(launch/list/get/cancel), user-channel WS. Contracts: two flow_run_* frames.
Web: orchestrator pane kind + OrchestratorPane, Workflow button + slash flows
(BooChat/BooCoder parity), FlowLauncherDialog, "New Orchestrator" in the + and
split menus, runs history + export. Plan: openspec/changes/orchestrator.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/coder/src/conductor/flows/investigate.ts

@@ -0,0 +1,27 @@
+import type { Spine, StepContext } from '../types.js';
+
+const q = (ctx: StepContext) => String(ctx.input.question);
+const repoLine = (ctx: StepContext) => (ctx.input.repoPath ? ` Repo: ${String(ctx.input.repoPath)}.` : '');
+
+/** Han `investigate` — root-cause a bug/failure from concrete evidence. */
+export const investigate: Spine = {
+  name: 'investigate',
+  description: 'root-cause a bug/failure from evidence',
+  angles: [
+    {
+      id: 'investigator',
+      agent: 'evidence-based-investigator',
+      label: 'Investigation (evidence-based-investigator)',
+      task: (ctx) =>
+        `Investigate the issue below. Gather concrete evidence — file:line, error text, git history, test coverage — and propose the most likely root cause with the evidence chain for it.${repoLine(ctx)}\n\nISSUE: ${q(ctx)}`,
+    },
+    {
+      id: 'edges',
+      agent: 'edge-case-explorer',
+      label: 'Edge cases & failure modes (edge-case-explorer)',
+      minBand: 'medium',
+      task: (ctx) =>
+        `Catalog the edge cases and failure modes most relevant to the issue below — boundary values, external-input messiness, state-dependent failures, error-propagation gaps.${repoLine(ctx)}\n\nISSUE: ${q(ctx)}`,
+    },
+  ],
+};