feat(i18n): add German (de) locale support for badge labels (JhaSourav07#562)

## Description

Fixes JhaSourav07#313

## Pillar
- [x] 🛠️ Other (Bug fix, refactoring, docs)

## Visual Preview
*Pure backend translation extension inside internationalization record
mapping arrays.*

## 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(i18n): ...`).
- [x] I have updated `README.md` if I added a new theme or URL
parameter.
- [x] I have starred the repo.
- [x] I have made sure that i have only one commit to merge in this PR.
- [x] The SVG output matches the CommitPulse "premium quality" aesthetic
standard (no raw elements, smooth animations, correct fonts).
- [x] (Recommended) I joined the CommitPulse Discord community for
contributor discussions, mentorship, and faster PR support.

Author: atharv96k

README.md

@@ -155,7 +155,7 @@ URL Parameter > Theme Default > System Fallback
 | `hide_background` | `boolean` | No         | `false`                        | Remove the background rect, letting the monolith float on the page                                                                                                        |
 | `hide_stats`      | `boolean` | No         | `false`                        | Hides the bottom row displaying Current Streak, Annual Sync Total, and Peak Streak stats when set to `true` or `1`.                                                       |
 | `tz`              | `string`  | No         | Omitted = UTC                  | IANA timezone (e.g. `Asia/Kolkata`, `America/New_York`) — aligns "today" with the user local midnight. Note: `?tz=UTC` is valid but cached separately from omitting `tz`. |
-| `lang`            | `string`  | No         | `en`                           | Language code for labels (`en`, `es`, `hi`, `fr`, `pt`, `ko`, `ja`)                                                                                                       |
+| `lang`            | `string`  | No         | `en`                           | Language code for labels (`en`, `es`, `hi`, `fr`, `pt`, `ko`, `ja`, `de`)                                                                                                 |
 | `view`            | `string`  | No         | `default`                      | Rendering mode: `default` (3D Monolith) or `monthly` (Compact monthly stats)                                                                                              |
 | `delta_format`    | `string`  | No         | `percent`                      | Format for month-over-month delta in monthly view: `percent` (e.g. +12%), `absolute` (e.g. +15 commits), or `both`                                                        |
 | `width`           | `number`  | No         | `300`                          | Custom width for the SVG canvas (currently only applies to `view=monthly`)                                                                                                |

lib/i18n/badgeLabels.ts

@@ -56,6 +56,13 @@ export const labels: Record<string, BadgeLabels> = {
     COMMITS_THIS_MONTH: '今月のコミット数',
     VS_LAST_MONTH: '先月比',
   },
+  de: {
+    CURRENT_STREAK: 'AKTUELLE_SERIE',
+    ANNUAL_SYNC_TOTAL: 'JAHRES_GESAMT',
+    PEAK_STREAK: 'SPITZEN_SERIE',
+    COMMITS_THIS_MONTH: 'COMMITS DIESEN MONAT',
+    VS_LAST_MONTH: 'im Vgl. zum Vormonat',
+  },
 };
 
 export function getLabels(lang: string = 'en'): BadgeLabels {