[Improve] Add two-lane onboarding guidance to home

[roomote-roomote]

Created by Roomote. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

• Replaced the single onboarding prompt below the task composer with a full-width pane above the home-page task and pull request tabs.
• Added independent task and ambient priority lanes, including curated setup recommendations, cookbook recipes, and a direct contact action.
• Added per-lane completion states and a persisted pane-level collapse control that reduces the pane to one right-aligned expand icon.
• Removed the obsolete suggested-task query parameter and confirmation card from the setup-to-home flow.

Why this change was made

Actionable product setup and evergreen guidance have different lifecycles. Separating them keeps both useful without letting lower-value integration prompts dominate onboarding, while the collapse control lets returning users reclaim the space.

Impact

Home now shows one highest-priority recommendation from each lane side by side on desktop and stacked on mobile. Card dismissal behavior remains intact, integrations are limited to the curated set, and users who finish a lane see a stable completion state instead of the pane changing shape.

Screenshots

[roomote-community]

No code issues found. See task

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