#1414 Add instructions for injecting button and tab-specific side panel functionality Fixes #1179

[Anonymous]

Originally created by: GAURAVCHAWLA1808

This issue involves implementing the ability to inject a button into specific websites and open a tab-specific side panel in the Chrome extension. The button will be injected using a content script, and clicking on it will trigger the opening of a side panel unique to the current tab. The side panel's content will be loaded from a separate HTML file.

Additionally, a global side panel should be accessible via a context menu, which allows opening the side panel across all tabs in the current window.

Tasks:
Modify the content script to inject the button into the page.
Ensure that clicking the injected button opens a tab-specific side panel for the current tab.
Update the background script to handle context menu interactions for opening the global side panel.
Update the README to provide clear instructions for using both the injected button and context menu for opening side panels.
Expected Result:
Clicking the button injected into a page (e.g., Google) should open a tab-specific side panel.
The global side panel can be accessed via a context menu item.
Both features should function correctly, with the side panel's content changing based on the tab or context.