fix: enforce 100-character max length on goal title (closes #384

[MehtabSandhu11]

Summary

Neither the frontend input nor the POST /api/goals endpoint validated the length of the goal title. A very long title would be stored in the database and overflow the progress bar card layout, breaking the UI.

Changes

src/app/api/goals/route.ts

• Added a server-side guard in the POST handler: returns 400 with a descriptive error if title.trim().length > 100

src/components/GoalTracker.tsx

• Added maxLength={100} to the title <input> as a browser-level hard stop
• Added a live character counter ({n}/100) that turns red at 90+ characters to warn the user before they hit the limit
• Added inline error message below the input when the limit is exceeded
• Added client-side validation in handleCreate() to block submission without a network round-trip
• Updated the submit button's disabled condition to also block when a title error is present
• Added aria-describedby on the input pointing to the hint/counter element for accessibility

Behaviour

Scenario	Result
Title ≤ 100 chars	Works as before
Title 91–100 chars	Counter turns red, form still submits
Title > 100 chars	Inline error shown, submit blocked client-side
Direct API call with title > 100 chars	400 Bad Request with error message

Testing

• Typed a title over 100 characters — counter turns red and submit is disabled
• Submitted via form at exactly 100 characters — succeeds
• Sent a POST request directly to /api/goals with a 101-character title — returns 400
• npm run lint && npm run type-check pass with no new errors

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• level:intermediate — 35 pts
• level:advanced — 55 pts
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[Priyanshu-byte-coder]

Closing — the server-side validation here is a subset of what PR #469 already implements more thoroughly (full type checks, bounds, error handling). #469 has been merged. If you want to contribute the client-side character counter from this PR, please open a fresh PR against the updated main branch.