♻️ refactor: migrate all web apps to Phosphor icons

Replace lucide-svelte with @manacore/shared-icons across all web apps
for consistent icon usage throughout the monorepo.

Apps migrated:
- calendar (12 files)
- contacts (1 file)
- matrix (16 files)
- nutriphi (7 files)
- presi (6 files)
- questions (9 files)
- skilltree (9 files)
- storage (16 files)
- todo (package.json only)

Key icon mappings:
- Trash2 → Trash
- ChevronLeft/Right/Up/Down → CaretLeft/Right/Up/Down
- Search → MagnifyingGlass
- Settings → Gear
- Loader2 → CircleNotch
- AlertCircle → WarningCircle
- ExternalLink → ArrowSquareOut
- LogOut → SignOut

apps/skilltree/apps/web/package.json

@@ -32,11 +32,11 @@
 	},
 	"dependencies": {
 		"@manacore/shared-auth": "workspace:*",
+		"@manacore/shared-icons": "workspace:*",
 		"@manacore/shared-tailwind": "workspace:*",
 		"@manacore/shared-theme": "workspace:*",
 		"@manacore/shared-utils": "workspace:*",
 		"idb": "^8.0.0",
-		"lucide-svelte": "^0.556.0",
 		"uuid": "^11.0.0"
 	},
 	"type": "module"