refactor(streak): introduced zod schema for API parameter validation

[Subhooo5]

Description

Fixes #67

Introduces zod for strict validation of incoming URL parameters across all three API routes, replacing scattered manual searchParams.get() calls and if/else fallbacks with a single centralized schema.

• New file lib/validations.ts:
  Defines streakParamsSchema, githubParamsSchema, and ogParamsSchema using Zod. Default values (theme: "dark", scale: "linear", speed: "8s") are handled via Zod's .default(). Invalid speed and scale values silently fall back to their defaults using .catch() to preserve existing behavior. The user and username fields are required and return a structured JSON error if missing.

• Changes in app/api/streak/route.ts:
  Replaced all individual searchParams.get() calls with a single streakParamsSchema.safeParse() call at the top of the handler. If parsing fails (e.g. missing user), the route returns a clean structured JSON 400 error immediately before any GitHub API call is made. All downstream logic remains identical.

• Changes in app/api/github/route.ts:
  Replaced manual searchParams.get('username') and if (!username) check with githubParamsSchema.safeParse(). Returns a structured JSON 400 error if username is missing. All error handling and cache logic remains identical.

• Changes in app/api/og/route.tsx:
  Replaced searchParams.get('user') ?? 'unknown' with ogParamsSchema.parse(). Since user is optional with a default of 'unknown', this route never throws a validation error. All rendering logic remains identical.

• Added 4 additional optional properties — radius, font, year, and refresh {Other than the requested ones}.

• All Acceptance Criteria are met. 🚀

Pillar

• 🛠️ Other (Bug fix, refactoring, docs)

Visual Preview

Checklist before requesting a review:

• I have read the CONTRIBUTING.md file.
• I have tested these changes locally (localhost:3000/api/streak).
• I have run npm run format and npm run lint locally and resolved all errors.
• My commits follow the Conventional Commits format.
• I have started the repo.
• I have made sure that i have only one commit to merge in this PR.
• The SVG output matches the CommitPulse "premium quality" aesthetic standard (no raw elements, smooth animations, correct fonts).

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[Subhooo5]

Hey @JhaSourav07 , please feel free to review the PR and merge the same. It satisfies all the acceptance criteria. Thank you 🚀🫂.

[Subhooo5]

@JhaSourav07 I accidentally named the branch on my fork as feat/zod-param-validation instead of refactor/zod-param-validation . So is the PR ok to merge, or do I need to recreate the PR with the updated correct branch name? It would take me just a few clicks to recreate the PR. Please feel free to confirm if change is required. 🚀

[JhaSourav07]

@Subhooo5
Kindly look at the comment i have left in the issue

[JhaSourav07]

@harxhe

Can you please review this PR.

[Subhooo5]

@Subhooo5 Kindly look at the comment i have left in the issue

All Done @JhaSourav07 🚀. Feel free to check and authorize.

[JhaSourav07]

Hey @Subhooo5,

@harxhe will review your PR. Once he will Approve it i will merge it.
Till then can you make sure to keep the PR to 1 commit.