[NAV-002] Add route transition progress bar

[chev0004]

Outline

Summary

Adds a reusable top-of-screen route transition progress bar for localized app navigation. The PR also replaces the toast viewport wrapper to avoid the Radix ref update loop that caused the Discovery page runtime error.

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Changes & Enhancements

• Type of Change:
  • Feature
  • Bugfix
  • Refactor
  • Chore
• Changes:
  • Navigation:
    • Added a route progress provider with pathname completion, guarded fallback cleanup, and primary-accent styling.
  • Routes:
    • Routed navbar, menu, language switcher, onboarding, profile, saved, settings, and discovery client navigation through the progress-aware router.
  • Toast:
    • Replaced the Radix toast viewport dependency with the app's native toast stack markup to prevent the maximum update depth crash.

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Page / App Changes

Affected Next.js Routes (Local):
/en
/en/profile
/en/saved
/en/settings
/en/onboarding

Before (Screenshot)

After (Screenshot)

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Component / Storybook Changes

Affected Storybook Components (Local):

• Components/Toast > Default
• Components/Toast > Auto Dismiss
• Features/Inbox > Live Update

Before (Screenshot)

After (Screenshot)

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Not Doing

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Other (Remarks)

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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.