Amaresh: Add POST /badge/assign endpoint for multi-user badge assignment

[amaresh2001]

Description

The Badge Assignment feature on the frontend lets an admin select multiple users and multiple badges and assign them in one action. The frontend action assignBadgesToMultipleUserID sends POST /api/badge/assign with { userIds, selectedBadges }, but that route never existed on the backend; only the single-user PUT /api/badge/assign/:userId did. Every bulk assignment hit a 404, and the UI showed "Oops, something went wrong while assigning badges!".

This PR adds the missing endpoint.

Fixes the badge-assignment failure reported on frontend PR #4734

Related PRS (if any):

Paired with frontend PR OneCommunityGlobal/HighestGoodNetworkApp#4734 (branch Amalesh-3940-bugfix).
To test this backend PR you need to check out the #4734 frontend branch and run it against this backend branch.

Main changes explained:

• Update src/controllers/badgeController.js: add assignBadgesToMultipleUsers:
  • Requires the assignBadges permission (403 otherwise)
  • Validates userIds and selectedBadges are non-empty arrays (400 otherwise)
  • For each user, for each selected badge: increments count and pushes a new earnedDate if the user already has that badge; otherwise, adds a new badgeCollection entry with count: 1 and featured: false; bumps badgeCount by selectedBadges.length; clears that user's cache
  • Per-user try/catch so one bad ID does not fail the whole batch; returns 200 with a per-user results array, and 400 only if every user failed
• Update src/routes/badgeRouter.js: wire POST /badge/assign to controller.assignBadgesToMultipleUsers (added alongside the existing PUT /badge/assign/:userId)

How to test:

1. Check out this branch (amaresh/badge-assign-multiple-users) in HGNRest, run npm install, then npm run dev (backend on http://localhost:4500)
2. In HighestGoodNetworkApp, check out Amalesh-3940-bugfix, run npm install, then npm run start:local (frontend on http://localhost:5173)
3. Clear site data / cache, log in as an Admin or Owner account (needs the assignBadges permission)
4. Go to /badgemanagement → Badge Assignment tab
5. Search a name, tick 2+ users → the status line should read N user(s) selected
6. Click Assign Badge, tick 1+ badges → status line shows N badge(s) selected
7. Click Confirm → expected: green success alert "Awesomesauce! ...for multiple users!" (not the red "Oops" error)
8. Open one of the selected users' profiles → Featured Badges section shows the assigned badge with the correct count; assigning increments the count again rather than adding a duplicate entry
9. Repeat as an Owner and as an Admin; both succeed. A user without assignBadges gets a 403.

Screenshots or videos of changes:

Note:

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
98.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud