feat(flows): add YAML flow format, flow-runner, and /agent/v1/flow endpoint

- ops-agent/src/lib/flow-runner.ts: loads YAML flows, validates all steps
  against the command whitelist, executes sequentially; supports dry_run
  (emits WOULD RUN lines) and on_failure: abort|continue per step
- ops-agent/src/routes/flow.ts: POST /agent/v1/flow { flow_key, dry_run }
  streams step_start/stdout/stderr/step_done/done SSE events
- ops-agent/src/index.ts: register flow route, add FLOWS_PATH env var
- ops-agent/flows.example/: three flow definitions — update_scrum4me_web,
  update_mcp_worker, update_caddy_config; deploy to /etc/ops-agent/flows/
- ops-agent/commands.yml.example: add curl_smoke_scrum4me_web and
  docker_compose_ps_worker smoke-test commands
- app/api/flows/run/route.ts: Next.js proxy — creates FlowRun/FlowStep
  DB records per step, forwards SSE stream to browser
- hooks/useFlowRun.ts: add startFlow(flowKey, dryRun) method; handle
  step_start events to display step headers in the terminal
- components/StreamingTerminal.tsx: add 'info' line type (sky-400) for
  step headers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/StreamingTerminal.tsx

@@ -3,7 +3,7 @@
 import { useEffect, useRef } from 'react'
 
 export type TerminalLine = {
-  type: 'stdout' | 'stderr'
+  type: 'stdout' | 'stderr' | 'info'
   text: string
 }
 
@@ -75,7 +75,11 @@ export default function StreamingTerminal({ lines, status, error, className = ''
             key={i}
             className={
               'whitespace-pre-wrap break-all leading-5 ' +
-              (line.type === 'stderr' ? 'text-red-400' : 'text-zinc-100')
+              (line.type === 'stderr'
+                ? 'text-red-400'
+                : line.type === 'info'
+                  ? 'text-sky-400'
+                  : 'text-zinc-100')
             }
           >
             {line.text}