refactor: enforce stricter type hints (#91)

LSP was screaming at me so I decided to just address it to get it off my
screen.

+ Fixed the type hints
:= Modified and added type hints for certain functions and variables in
most of the files in the utils/ folder (and some in the subcommands/
folder) for clarity and so pyright's type checker wouldn't cry.
:+ To resolve certain type issues, I had to add a bit more tiny
additional code such as, additional checks if a variable is None, a tiny
class in utils/material/generator.py to resolve the constructor usage
mismatch between what the DynamicScheme accepts and what the code
actually passes, and etc.
- Renamed certain functions and variables for clarity and also for some
to not collide with pre-existing definitions from well-known library
imports.
+ PIL has reorganized their code a bit, so the code is made to reflect
their new definitions.
= Reorganized the single import statement for "colourfulness" in
utils/wallpaper.py to be close to the top.
(I think that's it)

Side Effects?:
Everything should work the same as no logic change was done whatsover
(unless we consider the added if statements for type checking as a logic
change). I've tested it, everything seems to be in urdir.

src/caelestia/utils/scheme.py

@@ -1,6 +1,7 @@
 import json
 import random
 from pathlib import Path
+from typing import Any
 
 from caelestia.utils.notify import notify
 from caelestia.utils.paths import atomic_dump, scheme_data_dir, scheme_path
@@ -14,19 +15,19 @@ class Scheme:
     _colours: dict[str, str]
     notify: bool
 
-    def __init__(self, json: dict[str, any] | None) -> None:
-        if json is None:
+    def __init__(self, scheme_json: dict[str, Any] | None) -> None:
+        if scheme_json is None:
             self._name = "catppuccin"
             self._flavour = "mocha"
             self._mode = "dark"
             self._variant = "tonalspot"
             self._colours = read_colours_from_file(self.get_colours_path())
         else:
-            self._name = json["name"]
-            self._flavour = json["flavour"]
-            self._mode = json["mode"]
-            self._variant = json["variant"]
-            self._colours = json["colours"]
+            self._name = scheme_json["name"]
+            self._flavour = scheme_json["flavour"]
+            self._mode = scheme_json["mode"]
+            self._variant = scheme_json["variant"]
+            self._colours = scheme_json["colours"]
         self.notify = False
 
     @property
@@ -196,7 +197,7 @@ scheme_variants = [
     "content",
 ]
 
-scheme: Scheme = None
+scheme: Scheme | None = None
 
 
 def read_colours_from_file(path: Path) -> dict[str, str]:
@@ -225,7 +226,7 @@ def get_scheme_names() -> list[str]:
     return [*(f.name for f in scheme_data_dir.iterdir() if f.is_dir()), "dynamic"]
 
 
-def get_scheme_flavours(name: str = None) -> list[str]:
+def get_scheme_flavours(name: str | None = None) -> list[str]:
     if name is None:
         name = get_scheme().name
 
@@ -234,11 +235,11 @@ def get_scheme_flavours(name: str = None) -> list[str]:
     )
 
 
-def get_scheme_modes(name: str = None, flavour: str = None) -> list[str]:
-    if name is None:
+def get_scheme_modes(name: str | None = None, flavour: str | None = None) -> list[str]:
+    if name is None or flavour is None:
         scheme = get_scheme()
-        name = scheme.name
-        flavour = scheme.flavour
+        name = name or scheme.name
+        flavour = flavour or scheme.flavour
 
     if name == "dynamic":
         return ["light", "dark"]