#4177 fix(desktop): stop auto-opting users into v2 + onboarding

Summary

• Fresh installs were being auto-flipped to optInV2: true and then force-walked through the experimental /setup/* onboarding flow on first launch. Both behaviors are removed — v2 and onboarding are explicit-opt-in only via Settings → Experimental.
• Deletes V2DefaultResolver, useIsFreshInstall, the isFreshInstall store field, the redirect block in _authenticated/layout.tsx, and the projects.hasAny / workspaces.hasAny tRPC procedures (all unused once the auto-flip is gone).
• Preserves the v2 toggle and "Restart onboarding" action in Settings → Experimental, the full /setup/* route tree, and any persisted optInV2: true from users who explicitly toggled.

Test plan

• Fresh install (clear v2-local-override-v2 localStorage): launches into v1 dashboard, no /setup/* redirect.
• Existing v1 user (projects/workspaces in localdb, no persisted override): stays on v1.
• User who toggled v2 on under Settings → Experimental: stays on v2 across launches, lands on the dashboard (not setup).
• Settings → Experimental → "Restart onboarding" still walks through /setup/providers → ... when v2 is on.
• Toggle v2 off in Experimental: surface flips back to v1 immediately.

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Summary by cubic

Stops auto-opting fresh installs into v2 and removes the forced /setup/* onboarding. v2 and onboarding are now explicit opt-in via Settings → Experimental; all users land on the dashboard.

• Bug Fixes

  • Removed first-launch redirect to /setup/* and the fresh-install auto-set of v2.
  • Kept existing optInV2 values in v2-local-override-v2 to avoid resetting explicit opt-ins; recently auto-flipped installs will remain on v2 unless toggled off.

• Refactors

  • Deleted V2DefaultResolver, useIsFreshInstall, and the isFreshInstall field from the v2-local-override store.
  • Removed unused tRPC procedures projects.hasAny and workspaces.hasAny.

Summary by CodeRabbit

• Refactor

  • Removed fresh-install detection and its initialization flow
  • Persisted workspace list now respects tab order
  • Local defaults state simplified to only store opt-in choice
  • Removed several unused internal query endpoints and re-exports

• Bug Fix

  • Eliminated an onboarding redirect that relied on the removed fresh-install logic