feat(bsky_api): add configurable host url for bluesky client

Make the Bluesky API host URL configurable through environment variable BSKY_HOST_URL
Remove redundant dotenv import since environment variables are already loaded

README.md

···
    CHAR_LIMIT=280
    SRC_APP_PASS=your_source_app_password
    DST_APP_PASS=your_destination_app_password
+   BSKY_HOST_URL=https://bsky.social # Optional: defaults to bsky.social
    ```
 
 ## Usage

src/bsky_api.py

···
 from atproto import IdResolver, Client
 import os
-import dotenv
 import logging
 
 # Ensure the log directory exists
···
 
 def login(handle_env_var, app_pass_env_var):
     try:
-        dotenv.load_dotenv()
         handle = os.getenv(handle_env_var)
         app_pass = os.getenv(app_pass_env_var)
+        host_url = os.getenv("BSKY_HOST_URL", "https://bsky.social")
+
+        client = Client(host_url)
 
         if not handle or not app_pass:
             logging.error("Handle or app password missing in environment variables.")
             raise ValueError("Handle or app password missing in environment variables")
 
         logging.debug("Attempting to log in with handle: %s", handle)
-        client = Client()
         client.login(handle, app_pass)  # Access credentials securely
 
         logging.info("Login successful for handle: %s", handle)

src/example.env.txt

···
 SRC_APP_PASS=your_bluesky_app_password
 DST_APP_PASS=your_bluesky_app_password
 DESTINATION_HANDLE=destination_bluesky_handle
-CHAR_LIMIT=280
+CHAR_LIMIT=280
+BSKY_HOST_URL=https://bsky.social