docs(types): add JSDoc comments to all interfaces in types/index.ts (JhaSourav07#815)

## Description
Fixes JhaSourav07#518

Adds JSDoc `/** */` comments to every field in all interfaces in
`types/index.ts` — `StreakStats`, `BadgeTheme`, `ContributionDay`,
`ContributionWeek`, `ContributionCalendar`, `MonthlyStats`, and
`BadgeParams` — so IDE autocomplete and new contributors immediately
understand each field's purpose without consulting the README.

## Pillar
- [ ] 🎨 Pillar 1 — New Theme Design
- [ ] 📐 Pillar 2 — Geometric SVG Improvement
- [ ] 🕐 Pillar 3 — Timezone Logic Optimization
- [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview
N/A — documentation-only change, no SVG output affected.

## Checklist before requesting a review:
- [x] I have read the `CONTRIBUTING.md` file.
- [x] I have tested these changes locally
(`localhost:3000/api/streak?user=YOUR_USERNAME`).
- [x] I have run `npm run format` and `npm run lint` locally and
resolved all errors (CI will fail otherwise).
- [x] My commits follow the Conventional Commits format (e.g.,
`feat(themes): ...`, `fix(calculate): ...`).
- [ ] I have updated `README.md` if I added a new theme or URL
parameter.
- [x] I have started the repo.
- [x] 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).
- [ ] (Recommended) I joined the CommitPulse Discord server for faster
collaboration, mentorship, and PR support.

Author: DharshiniPujarolla

types/index.ts

@@ -1,58 +1,145 @@
 export type HexColor = string & { __brand: 'HexColor' };
 
+/**
+ * Processed streak statistics calculated from the user's GitHub contribution data.
+ */
 export interface StreakStats {
+  /** The user's current active streak in days. Resets to 0 if no contributions today or yesterday. */
   currentStreak: number;
+
+  /** The user's all-time longest streak in days. */
   longestStreak: number;
+
+  /** Total number of contributions in the queried period. */
   totalContributions: number;
-  todayDate: string; // local calendar date used as "today" (YYYY-MM-DD)
+
+  /** Local calendar date used as "today" for streak calculation (format: YYYY-MM-DD). */
+  todayDate: string;
 }
 
+/**
+ * Resolved color palette for a badge theme after URL parameter overrides have been applied.
+ */
 export interface BadgeTheme {
+  /** Background fill color as a hex string WITHOUT the leading '#' (e.g. '0d1117'). */
   bg: HexColor;
+
+  /** Label and stat text color as a hex string WITHOUT the leading '#' (e.g. 'ffffff'). */
   text: HexColor;
+
+  /** Tower and glow accent color as a hex string WITHOUT the leading '#' (e.g. '58a6ff'). */
   accent: HexColor;
 }
 
+/**
+ * Represents a single day's contribution data returned from the GitHub GraphQL API.
+ */
 export interface ContributionDay {
+  /** Number of contributions made on this day. */
   contributionCount: number;
+
+  /** Calendar date of this contribution entry (format: YYYY-MM-DD). */
   date: string;
 }
 
+/**
+ * Represents a single week's worth of contribution days.
+ */
 export interface ContributionWeek {
+  /** Array of contribution day entries for this week, ordered Sunday to Saturday. */
   contributionDays: ContributionDay[];
 }
 
+/**
+ * Full contribution calendar returned from the GitHub GraphQL API.
+ */
 export interface ContributionCalendar {
+  /** Total number of contributions across all weeks in this calendar. */
   totalContributions: number;
+
+  /** Array of weekly contribution data covering the queried date range. */
   weeks: ContributionWeek[];
 }
 
+/**
+ * Month-over-month contribution statistics used by the monthly view.
+ */
 export interface MonthlyStats {
+  /** Total number of contributions in the current calendar month. */
   currentMonthTotal: number;
+
+  /** Total number of contributions in the previous calendar month. */
   previousMonthTotal: number;
+
+  /** Percentage change in contributions compared to the previous month (can be negative). */
   deltaPercentage: number;
+
+  /** Absolute change in contribution count compared to the previous month (can be negative). */
   deltaAbsolute: number;
+
+  /** Human-readable name of the current month (e.g. 'January', 'February'). */
   currentMonthName: string;
 }
 
+/**
+ * Parameters accepted by the /api/streak endpoint.
+ * All fields except `user` are optional; URL parameters override theme defaults.
+ */
 export interface BadgeParams {
+  /** GitHub username whose contribution data will be fetched and rendered. Required. */
   user: string;
+
+  /** Number of grace days before a streak resets (handles timezone edge cases). Defaults to 1. */
+  grace?: number;
+
+  /** Background fill color as a hex string WITHOUT the leading '#'. Overrides theme default. */
   bg: HexColor;
+
+  /** Label and stat text color as a hex string WITHOUT the leading '#'. Overrides theme default. */
   text: HexColor;
+
+  /** Tower and glow accent color as a hex string WITHOUT the leading '#'. Overrides theme default. */
   accent: HexColor;
+
+  /** Duration of the radar scan line animation (e.g. '4s', '8s', '12s'). Defaults to '8s'. */
   speed: string;
+
+  /** Tower height scaling algorithm. 'linear' scales proportionally; 'log' uses logarithmic scale for high contributors. Defaults to 'linear'. */
   scale: 'linear' | 'log';
+
+  /** Font family override for badge typography (e.g. 'monospace'). Defaults to theme font. */
   font?: string;
+
+  /** Border corner radius in pixels. Defaults to 8. */
   radius?: number;
+
+  /** When true, automatically selects a theme based on the viewer's system color scheme. */
   autoTheme?: boolean;
+
+  /** When true, hides the username title from the badge. */
   hide_title?: boolean;
+
+  /** When true, renders the badge without a background card. */
   hideBackground?: boolean;
+
+  /** When true, hides the streak and contribution stat numbers from the badge. */
   hide_stats?: boolean;
+
+  /** Language/locale code for stat labels (e.g. 'en', 'fr', 'ja'). Defaults to 'en'. */
   lang?: string;
+
+  /** Badge layout variant. 'default' shows the isometric monolith; 'monthly' shows month-over-month stats. */
   view?: 'default' | 'monthly';
+
+  /** Format for the monthly delta indicator. 'percent' shows %, 'absolute' shows raw count, 'both' shows both. */
   delta_format?: 'percent' | 'absolute' | 'both';
+
+  /** Custom width of the badge in pixels. Defaults to theme preset. */
   width?: number;
+
+  /** Custom height of the badge in pixels. Defaults to theme preset. */
   height?: number;
+
+  /** Preset size of the badge. 'small', 'medium', or 'large'. Overrides width and height. */
   size?: 'small' | 'medium' | 'large';
-  grace?: number;
 }