feat: Harness onboarding wizard + omp/dsh session sources

[kesslerio]

TL;DR

This PR adds the full harness/session stack to sparkDash: five coding-agent harness sources (OpenClaw, Hermes, OpenCode, oh-my-pi, DeepSeek Harness), a 3-step onboarding wizard, live session occupancy on LLM cards, and occupancy helper docs. Reviewers can connect their harnesses in under a minute and see which sessions are active on each Spark.

What Problem This Solves

sparkDash showed GPU and model metrics but had no visibility into which coding-agent sessions were running on each LLM port. Operators had to SSH into boxes or check each harness separately to know what was active. There was also no guided setup — connecting a harness required editing config files by hand.

Why This Change Was Made

I run multiple coding-agent harnesses across my fleet and wanted dashboard-level visibility into active sessions without leaving sparkDash. The wizard makes onboarding self-service for anyone I share the dashboard with. The occupancy helpers are part of the same feature surface, so their docs are folded in here rather than split into a separate PR.

User Impact

• New "Manage harnesses" button in the header opens a wizard (pick → configure → review)
• Each LLM card shows a conversation list with pulsating dots for generating/recent sessions
• Five harness types supported: OpenClaw (native API), Hermes (native API), OpenCode (helper), oh-my-pi (helper), DeepSeek Harness (helper, remote-only)
• Local and remote connection modes per harness, with agent-pasteable helper snippets
• UI renamed from "occupancy source" to "harness" throughout

Risk and Rollout

Low risk — this is additive (new session source collectors and a wizard modal). No existing behavior changes except the UI label rename. No migration needed; session sources default to empty. The occupancyHosts fix corrects a projector bug that was replacing existing hosts instead of merging. Rollout is opt-in: users connect harnesses via the wizard when ready.

Screenshots

Step 1 — Pick harnesses

Step 2 — Configure (local mode)

Step 2 — Configure (remote mode)

Step 3 — Review and save

Cleanshot

Demo

Feature demo video — wizard walkthrough

Evidence

• npm run typecheck — passes clean
• npm run build — passes (61 modules, 441 KB JS bundle)
• npm test — 370 server tests + 14 frontend tests pass (384 total, 0 fail)
• No bench/probe code leaked: git diff upstream/main..feat/harness-session-wizard -- server/collectors/LlmProbe.js is empty
• git diff upstream/main..feat/harness-session-wizard -- src/components/SparkPage/BenchmarkDialog.tsx is empty
• Gitleaks scan clean on commit
• Wizard verified via agent-browser: opens from header button, all 5 harnesses visible, local/remote modes render correctly, review step shows selected harnesses