feat: pre-calculate leaderboard ranks and update user endpoints and UI

[Yashaswini-K-P]

Description

This PR restructures individual user profile files to store pre-calculated leaderboard rankings (overall, daily, weekly, and monthly) directly within the data repository sync loop.

This addresses a critical architectural constraint: because the API layer (fetchUserInfo) is stateless and lacks a database, it cannot compute relative user standings on the fly. By pre-calculating and saving these ranks during the automated sync process, the API can now cheaply and instantaneously serve up-to-date ranks and changes directly to the profile UI from a single file fetch.

Linked Issue

Fixes #195

Changes Made

• Updated the backend sync script to pull user leaderboard standings across all historical intervals.
• Appended a new leaderboardRanks metadata block directly onto individual user JSON profiles without breaking existing history streams.
• Updated fetchUserInfo in the API service to parse the new object structure and inject actual rank metrics and trend trajectories into the payload.

Type of Change

• Bug fix
• New feature
• UI/Visual update
• Documentation update
• Refactor

Testing

• Tested locally
• Tested on mobile viewport (if applicable)
• No console errors introduced

Checklist

• My code follows the project's coding style
• I have formatted my code locally by running npx prettier --write . before submitting
• I am submitting my PR from a dedicated feature/* branch, not the main branch
• I have performed a self-review of my code
• My changes generate no new warnings or errors
• I have updated documentation if required
• I have linked the relevant issue

Screenshots / Screen Recording

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[jagdish-15]

@Yashaswini-K-P

Could you please check and resolve these merge conflicts?