fix: mark posthog-node as a peer dependency (#12539)

Since the runtime of the `@medusajs/analytics-posthog` relies on `posthog-node` package. It should be either installed as a dependency or a peerDependency that will be satisfied by the user project.

In this PR, I have added it as a peer dependency

.changeset/empty-peas-cheer.md

@@ -0,0 +1,6 @@
+---
+"@medusajs/medusa": patch
+"@medusajs/analytics-posthog": patch
+---
+
+fix: mark posthog-node as a peer dependency

packages/medusa/package.json

@@ -140,6 +140,7 @@
     "@opentelemetry/sdk-trace-node": "^2.0.0",
     "@swc/core": "1.5.7",
     "awilix": "^8.0.1",
+    "posthog-node": "^4.17.1",
     "react-dom": "^18.0.0",
     "yalc": "1.0.0-pre.53"
   },
@@ -159,6 +160,9 @@
     "@swc/core": {
       "optional": true
     },
+    "posthog-node": {
+      "optional": true
+    },
     "react-dom": {
       "optional": true
     },

packages/modules/providers/analytics-posthog/package.json

@@ -34,7 +34,8 @@
     "typescript": "^5.6.2"
   },
   "peerDependencies": {
-    "@medusajs/framework": "2.8.2"
+    "@medusajs/framework": "2.8.2",
+    "posthog-node": "^4.17.1"
   },
   "keywords": [
     "medusa-plugin",

yarn.lock

@@ -5848,6 +5848,7 @@ __metadata:
     typescript: ^5.6.2
   peerDependencies:
     "@medusajs/framework": 2.8.2
+    posthog-node: ^4.17.1
   languageName: unknown
   linkType: soft
 
@@ -6722,6 +6723,7 @@ __metadata:
     "@opentelemetry/sdk-trace-node": ^2.0.0
     "@swc/core": 1.5.7
     awilix: ^8.0.1
+    posthog-node: ^4.17.1
     react-dom: ^18.0.0
     yalc: 1.0.0-pre.53
   peerDependenciesMeta:
@@ -6735,6 +6737,8 @@ __metadata:
       optional: true
     "@swc/core":
       optional: true
+    posthog-node:
+      optional: true
     react-dom:
       optional: true
     yalc: