Add API v1 deprecation banners (calcom#25065)

* Update docs/api-reference/v1/introduction.mdx

* Update docs/api-reference/v1/authentication.mdx

* Update docs/api-reference/v1/errors.mdx

* Update docs/api-reference/v1/rate-limit.mdx

* Update docs/mint.json

---------

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

Author: mintlify[bot]

docs/api-reference/v1/authentication.mdx

@@ -2,6 +2,10 @@
 title: "Authentication"
 ---
 
+<Warning>
+**API v1 is deprecated and will be discontinued on February 15, 2026.** Please migrate to [API v2](/api-reference/v2/introduction) as soon as possible.
+</Warning>
+
 The Cal.com API uses API keys to authenticate requests. You can view and manage your API keys in your settings page under the security tab in Cal.com.
 
 <img src="/images/i1600x899-DllqhV6w_3Vj_oxtjov.png" />

docs/api-reference/v1/errors.mdx

@@ -2,6 +2,10 @@
 title: "Errors"
 ---
 
+<Warning>
+**API v1 is deprecated and will be discontinued on February 15, 2026.** Please migrate to [API v2](/api-reference/v2/introduction) as soon as possible.
+</Warning>
+
 Cal.com uses conventional HTTP response codes to indicate the success or failure of an API request. In general: Codes in the 2xx range indicate success. Codes in the 4xx range indicate an error that failed given the information provided (e.g., a required parameter was omitted, or something else failed, etc.). Codes in the 5xx range indicate an error with Cal.com's servers (these are rare).
 
 <table>

docs/api-reference/v1/introduction.mdx

@@ -2,6 +2,10 @@
 title: "Quick start"
 ---
 
+<Warning>
+**API v1 is deprecated and will be discontinued on February 15, 2026.** Please migrate to [API v2](/api-reference/v2/introduction) as soon as possible.
+</Warning>
+
 ## Get your API keys
 
 Your API requests are authenticated using API keys. Any request that doesn't include an API key will return an error.

docs/api-reference/v1/rate-limit.mdx

@@ -2,6 +2,10 @@
 title: "Rate limits"
 ---
 
+<Warning>
+**API v1 is deprecated and will be discontinued on February 15, 2026.** Please migrate to [API v2](/api-reference/v2/introduction) as soon as possible.
+</Warning>
+
 We limit the number of calls you can make over a certain period of time. Rate limits vary and are specified by the following header in all responses:
 
 <table>

docs/mint.json

@@ -52,7 +52,11 @@
     {
       "name": "API v1 Reference",
       "openapi": "/api-reference/v1/openapi-v1.json",
-      "url": "api-reference/v1"
+      "url": "api-reference/v1",
+      "banner": {
+        "type": "warning",
+        "content": "API v1 will be discontinued on February 15, 2026. Please migrate to [API v2](/api-reference/v2/introduction)."
+      }
     }
   ],
   "navigation": [