Update API project documentation

API.md

@@ -111,6 +111,14 @@ Query parameters:
 
 Response: list of creator cards including follow state and avatar URL.
 
+### Public Profile
+
+```http
+GET /api/v1/profiles/{creatorId}
+```
+
+Used by public creator profiles. The response contains display name, slug, bio, avatar URL, average rating and subscriber count.
+
 ### Update Profile
 
 ```http
@@ -144,6 +152,8 @@ GET /api/v1/prompts?sortBy=date&ascending=false&limit=50&search=cat
 
 Used by Marketplace. Supports sorting, search and category filtering.
 
+Response items include prompt title, description, creator id, creator name, creator avatar, example image, price, like/save counts and access state.
+
 ### Feed
 
 ```http
@@ -177,6 +187,23 @@ Request:
 
 Response: created prompt. The frontend redirects to `/post-detail?id={id}`.
 
+### Own Prompts
+
+```http
+GET /api/v1/prompts/mine
+```
+
+Used by My Profile to show prompts created by the logged-in user.
+
+### Update Prompt
+
+```http
+PUT /api/v1/prompts/{id}
+Content-Type: application/json
+```
+
+Request body uses the same editable fields as prompt creation. Used by the edit prompt flow.
+
 ### Prompt Detail
 
 ```http
@@ -193,6 +220,20 @@ Response includes:
 - example output
 - example image
 - rating data
+- like/save state and counts
+
+Paid prompts return no detail content for users without access.
+
+### Likes and Saves
+
+```http
+PUT /api/v1/prompts/{id}/likes
+DELETE /api/v1/prompts/{id}/likes
+PUT /api/v1/prompts/{id}/saves
+DELETE /api/v1/prompts/{id}/saves
+```
+
+Used by Dashboard, prompt detail and profile tabs to store user interactions.
 
 ### Reviews
 
@@ -240,8 +281,20 @@ Default categories are created automatically when the backend starts.
 ### Follow or Subscribe to Creator
 
 ```http
+GET /api/v1/subscriptions/{creatorId}
 PUT /api/v1/subscriptions/{creatorId}
 DELETE /api/v1/subscriptions/{creatorId}
 ```
 
-Used by Community to follow or unfollow creators.
+Used by Community and public profiles to read follow state, follow creators or unfollow creators.
+
+## Error Handling
+
+Common response codes used by the frontend:
+
+- `200 OK`: request succeeded
+- `400 Bad Request`: validation error or invalid request data
+- `401 Unauthorized`: user is not logged in and should be redirected to login
+- `404 Not Found`: requested prompt, profile or subscription was not found
+
+The frontend handles failed requests with visible error states or redirects to login for unauthorized users.