Onboarding: single-page flow

[talissoncosta]

Part of #7540.

The core experience: signup → connect your SDK → first evaluation → flip a real flag, all on one page. Most of it already exists on feat/onboarding-quickstart-7182; this issue is about landing it and wiring the real connected state.

Scope

• Resource bootstrap — idempotently reuse-or-create org / project / Development + Production environments / first flag (no duplicates on revisit).
• Loading splash — lazy-loaded Lottie "Setting up your workspace".
• Editable resources — inline org / project rename; flag rename (delete + recreate, using the create-feature name rule).
• Connect panel — "Connect with AI" (agent-agnostic, zero-auth prompt with the env key + flag) and a manual tab with an all-SDK selector (quick chips + "More" accordion, snippets from Constants.codeHelp).
• Verify console — honest listening state (env target + checklist + typewriter + pulsing "LISTENING") that flips to a connected receipt driven by the real first-evaluation signal. Never faked.
• Flags table — centred table reusing the product's FeatureName / Tag / FeatureDescription / Switch; real toggle persistence (Dev env); highlighted when connected, greyed out while waiting.
• Gating — render behind the existing Flagsmith-on-Flagsmith flag (the prototype one) so it's A/B-able with a percentage rollout.

Done when

• The flow works end-to-end against a real backend; toggling the flag persists.
• It renders only behind the FoF flag (percentage rollout for the A/B).
• The connected state fires from the real first-SDK-evaluation signal (Onboarding: track first SDK evaluation received #7623), not a preview.
• No simulated SDK output anywhere — honesty is preserved throughout.

Depends on #7623 for the real connected transition.