huge refactor of the entire codebase, with the goal of improving maintainability, readability, and extensibility. This commit includes changes to almost every file in the project, including:

docs/result_table.md

@@ -40,7 +40,7 @@ from SYS.result_table import ResultTable
 table = ResultTable("Provider: X result").set_preserve_order(True)
 table.set_table("provider_name")
 table.set_table_metadata({"provider":"provider_name","view":"folders"})
-table.set_source_command("search-file", ["-provider","provider_name","query"])
+table.set_source_command("search-file", ["-plugin","provider_name","query"])
 
 for r in results:
     table.add_result(r)  # r can be a SearchResult, dict, or PipeObject
@@ -82,13 +82,13 @@ Example commands:
 
 ```
 # List magnets in your account
-search-file -provider alldebrid "*"
+search-file -plugin alldebrid "*"
 
 # Open magnet id 123 and list its files
-search-file -provider alldebrid -open 123 "*"
+search-file -plugin alldebrid -open 123 "*"
 
 # Or expand via @ selection (selector handles drilling):
-search-file -provider alldebrid "*"
+search-file -plugin alldebrid "*"
 @3  # selector will open the magnet referenced by row #3 and show the file table
 ```
 
@@ -147,7 +147,7 @@ Selection & download flows
 
 ```
 # Expand magnet and add first file to local directory
-search-file -provider alldebrid "*"
+search-file -plugin alldebrid "*"
 @3  # view files
 @1 | add-file -path C:\mydir
 ```
@@ -167,7 +167,7 @@ Example usage:
 
 ```
 # Search for an artist
-search-file -provider bandcamp "artist:radiohead"
+search-file -plugin bandcamp "artist:radiohead"
 
 # Select an artist row to expand into releases
 @1