fix(install): native-app installs read runtimeType from registry manifest

[samxu01]

Summary

• AgentRegistry row for each native first-party app now carries manifest.runtime = { type: 'native', runtimeType: 'native' } (the demo-pod seed already wrote this onto AgentInstallation; this lifts the declaration up to the registry where every install path can see it).
• /api/registry/install falls back to the registry manifest's runtime.runtimeType (or runtime.type) when the caller didn't supply one — symmetric with the demo-pod seed.

Why

Surfaced during the 2026-05-23 local UI smoke walkthrough. Installing pod-welcomer / task-clerk / pod-summarizer via /v2/agents/browse produced an AgentInstallation with config.runtime = {}. agentEventService.enqueue checks installation.config.runtime.runtimeType to decide whether to run the agent in-process via nativeRuntimeService.runAgent; with no value set, every chat.mention routed to the external pending queue (which has no listener for native apps), and the agent never replied.

The demo-pod seed in seed-native-agents.ts already wrote runtimeType: 'native' explicitly on the demo install, so the cluster's Team Orchestration Demo pod was unaffected. Every other install target — fresh local stack, freshly created pod via UI in dev — fell off the path silently.

Verification (local)

Fresh ./dev.sh up stack with LITELLM_BASE_URL + LITELLM_API_KEY wired to the dev cluster's LiteLLM (port-forwarded virtual key with $2 / 24h budget cap):

1. Install pod-welcomer via /v2/agents/browse → AgentInstallation.config.runtime.runtimeType === 'native' ✅
2. @pod-welcomer ping in the host pod → backend logs [agent-event] enqueued ... status=delivered (delivered = native dispatch path), then [agent-message] posted agent=pod-welcomer ✅
3. Chat surface shows the agent reply within ~5s ✅

Risk

Very narrow:

• The fallback only fires when both (a) caller didn't supply runtime.runtimeType AND (b) the manifest declares one. No existing installs change.
• Seed manifest change is additive ($set), idempotent, and the demo-pod install path's explicit runtimeType: 'native' is unaffected.

Test plan

• CI green
• Backend unit tests (no test changes; behavior is purely a default that fires when an existing field is missing)
• Manual dev verify: install pod-welcomer into any non-demo pod, send @pod-welcomer ping, confirm reply within ~10s

🤖 Generated with Claude Code

[samxu01]

Companion audit docs landed on this branch as a separate commit (docs/audits/ui-smoke-2026-05-23/). They capture the full walkthrough + 3 subagent gap reports (marketplace, settings, landing-v2 proposal) + recipes for the two runtime adapter paths verified locally.

If the docs are out of scope for this fix-PR, easy to drop with git rm -r docs/audits/ui-smoke-2026-05-23/ and force-push; they're additive.

[samxu01]

Merged via local squash to main (per repo convention preserving multi-author trailers). Final commit on main with all 8 co-authored changes from the smoke/ui-walkthrough-2026-05-23 branch. Closing PR + deleting branch.