[DISC-006] Add looking-for modes

[chev0004]

Outline

Summary

Adds structured looking-for modes so members can state the kind of language-partner interaction they want, shown on profiles and usable as a discovery filter.

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Changes & Enhancements

• Type of Change:
  • Feature
  • Bugfix
  • Refactor
  • Chore
• Changes:
  • (data):
    • Add a localized looking-for modes constant (casual chat, study buddy, voice practice, grammar help, gaming, exam prep, culture exchange).
    • Add a looking_for text array column to profiles with value and cardinality check constraints, plus migration 0004.
    • Thread modes through the profile schema, save route, profile loader, and discovery mapping.
  • (profile editor):
    • Add a multi-select LookingForEditor in the About Me section, reflected in the live card preview.
  • (discovery):
    • Show selected modes on the profile card through a compact LookingForRow.
    • Add a Looking For filter with URL state that matches profiles having any selected mode.

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Page / App Changes

Affected Next.js Routes (Local):

• /[lang] (discovery feed and filters)
• /[lang]/profile (profile editor)

Before (Screenshot)

After (Screenshot)

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Component / Storybook Changes

Affected Storybook Components (Local):

• Features/Profile/LookingForEditor > Empty
• Discovery/LookingForRow > Default
• Discovery/ProfileCard > Free Sky
• Components/Filter/FilterBar > Default

Before (Screenshot)

After (Screenshot)

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Not Doing

• Onboarding does not collect modes; new and existing profiles default to none and set them later in the profile editor.

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Other (Remarks)

• Requires bun run db:migrate on deploy to apply migration 0004_profile_looking_for, which adds the looking_for column.

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Checklists

• Code is well-documented (comments, JSDoc, etc.).
• Existing comments were updated as needed.
• No out-of-scope changes are included.
• Write TODO comments where future work is required.
• Removed unnecessary debug code (e.g., console.log, debugger).
• Self-reviewed and tested locally.