Add user-private links feature

[amalg]

Summary

This PR adds the ability for users to create their own personal dashboard links that are visible only to them. The feature includes an admin toggle to enable/disable it, and is disabled by default for a conservative deployment approach.

Key Features

• User-private links: Users can create personal links visible only to themselves
• Admin control: Toggle to enable/disable the feature globally (disabled by default)
• Configurable limit: Admins can set max links per user (1-50, default 10)
• Personal settings page: Users manage their links in Settings > DashLink
• Separate icon storage: User icons stored in user_icons/{userId}/ subfolder
• Dashboard integration: Admin links display first, then user links (max 10 total)
• Full functionality: CRUD, import/export, drag-drop reorder for user links
• Security: Rate limiting on link creation (20/hour) and import (3/hour)

Database Changes

New migration adds user_id column to dashlink_links table:

• NULL = admin/global link (existing behavior)
• Non-NULL = user's private link

New Files

Backend (PHP)

• lib/Migration/Version002Date20250210000000.php - Database migration
• lib/Service/UserLinkService.php - User link business logic
• lib/Controller/UserLinkController.php - REST API for user links
• lib/Settings/Personal.php - Personal settings page
• lib/Settings/PersonalSection.php - Settings section registration

Frontend (Vue.js)

• src/personal.js - Entry point for personal settings
• src/composables/useUserLinks.js - API composable for user links
• src/components/PersonalPanel.vue - Personal settings UI
• src/components/UserLinkForm.vue - Link form (simplified, no group picker)
• src/components/UserIconUploader.vue - Icon uploader for user links

Templates

• templates/personal.php - Personal settings mount point
• templates/personal-disabled.php - Shown when feature is disabled

API Endpoints Added

All user endpoints require authentication but not admin access:

Method	Endpoint	Description
GET	/api/v1/user/links	List user's links
POST	/api/v1/user/links	Create link
PUT	/api/v1/user/links/{id}	Update link
DELETE	/api/v1/user/links/{id}	Delete link
POST	/api/v1/user/links/{id}/icon	Upload icon
DELETE	/api/v1/user/links/{id}/icon	Delete icon
GET	/api/v1/user/links/{id}/icon	Get icon
PUT	/api/v1/user/links/order	Update order
GET	/api/v1/user/links/export	Export to JSON
POST	/api/v1/user/links/import	Import from JSON

Admin Settings

New options in Admin Settings > DashLink:

• Toggle: "Allow users to create personal links"
• Input: "Maximum links per user" (shown when enabled)

Test Plan

• Enable feature in admin panel
• As regular user, navigate to Personal Settings > DashLink
• Create a link with icon, verify it appears
• Verify link appears in dashboard after admin links
• Verify another user cannot see the link
• Disable feature in admin panel
• Verify Personal Settings > DashLink section disappears
• Verify user links no longer appear in dashboard
• Re-enable feature, verify links are restored
• Test link limit enforcement
• Test import/export for user links