#6122 feat(desktop): restore onboarding funnel instrumentation

Part of SUPER-1729 — https://linear.app/superset-sh/issue/SUPER-1729

Restores renderer-side onboarding funnel instrumentation for the 2-step flow. Analytics only — no UX, navigation, gating, or experiment changes (useNewWorkspaceScreenVariant and all new-workspace-screen exposure logic untouched). All events go through the existing track() helper in renderer/lib/analytics.

Events emitted

Event	Properties	When
onboarding_started	—	First entry into the onboarding flow; module-level guard prevents double-fire on remount/route bounce (once per renderer session)
onboarding_step_started	step	Entering a step; deduped against the current step, re-fires on re-entry after abandonment
onboarding_step_completed	step	Step 1: Continue click. Step 2: in finish() immediately before onboarding_finished
onboarding_abandoned	step	Best-effort on layout unmount (deferred one tick so StrictMode double-mounts and route bounces don't count) and synchronously on beforeunload; suppressed once finished
onboarding_error	step, action, reason	Clone failure (action: clone), completeOnboarding failure (action: complete_onboarding), gh auth exiting unauthenticated (action: gh_auth), provider API-key save failure (action: provider_connect)
onboarding_finished	outcome: completed	Unchanged — same call site, name, and timing as before
onboarding_provider_connected	provider, method	Pre-existing, unchanged

reason is always a machine-readable code mapped from the error (repo_not_found, auth_failed, network_error, already_exists, clone_failed, host_not_ready, api_unreachable, request_failed, auth_incomplete, api_key_failed) — never URLs, repo names, paths, or messages.

Step slugs

• Step 1 (tools/providers checklist) → providers — the historical providers step is the closest ancestor of this surface; the old gh-cli/permissions/adopt-worktrees steps no longer exist as separate screens, and gh-CLI issues remain distinguishable via onboarding_error with action: gh_auth.
• Step 2 (create/add a project) → project — exact match with the historical slug.

Verification

• bun run lint:fix → bun run lint exits 0; apps/desktop bun run typecheck clean. No colocated tests in the touched files.
• Verified end-to-end via CDP against the real dev app (renderer on this workspace's DESKTOP_VITE_PORT=3225, CDP 9615): posthog.capture was wrapped via Page.addScriptToEvaluateOnNewDocument so no test events reached production PostHog; onboarded_at was nulled for the dev user, the flow was walked with real UI clicks, then onboarded_at restored.

Captured sequence (in order, from window.__t5Events):

[{"event":"onboarding_started","props":null},
 {"event":"onboarding_step_started","props":{"step":"providers"}},
 {"event":"onboarding_step_completed","props":{"step":"providers"}},   // Continue click
 {"event":"onboarding_step_started","props":{"step":"project"}},
 {"event":"onboarding_error","props":{"step":"project","action":"clone","reason":"repo_not_found"}},  // clone of nonexistent repo
 {"event":"onboarding_abandoned","props":{"step":"project"}},          // beforeunload path
 {"event":"onboarding_step_started","props":{"step":"providers"}},     // re-entry via Back — note: no second onboarding_started
 {"event":"onboarding_step_completed","props":{"step":"providers"}},
 {"event":"onboarding_step_started","props":{"step":"project"}},
 {"event":"onboarding_step_completed","props":{"step":"project"}},
 {"event":"onboarding_finished","props":{"outcome":"completed"}}]      // real clone; app then redirected to #/v2-workspaces

The abandonment leg was triggered with a dispatched beforeunload event (synthetic — a real reload wipes the in-page capture buffer); the layout-unmount path uses the same flush and its timer-cancel behavior is exercised by the Back/Continue route changes above, which correctly did not emit onboarding_abandoned. Everything else was end-to-end UI interaction on the live app.

Kept intentionally additive for easy rebasing against #6116/#6117.

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Summary by cubic

Restores renderer-side onboarding funnel analytics for the 2-step flow to meet SUPER-1729. No UX, navigation, gating, or experiment changes; all events go through track().

• New Features
  • Emits: onboarding_started, onboarding_step_started, onboarding_step_completed, onboarding_abandoned, onboarding_error, and keeps onboarding_finished/onboarding_provider_connected as-is. Deduped per session and step.
  • Abandon tracking: flushed on beforeunload; scheduled on layout unmount and canceled on re-entry to avoid false positives.
  • Error tracking: { step, action, reason } with machine-readable reasons only (e.g., repo_not_found, auth_failed, api_unreachable, clone_failed, api_key_failed).
  • Step slugs: providers (tools/providers checklist) and project (create/add project).
  • Integrated at key points: provider API key save failures, GH auth exit unauthenticated, clone failures/host not ready, and completeOnboarding failures.

Summary by CodeRabbit

• Analytics
  • Added comprehensive onboarding progress tracking, including step entry, completion, abandonment, and overall completion.
  • Added error tracking for provider API-key connections, GitHub authentication, project setup, cloning, and host readiness.
  • Error reporting uses sanitized reason categories without exposing sensitive messages or paths.