chore: add necessary config files

.clang-format

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+---
+Language: Cpp
+BasedOnStyle: Google
+ColumnLimit: 0
+IndentWidth: 4
+AccessModifierOffset: -2
+NamespaceIndentation: All
+AlignOperands: AlignAfterOperator
+AllowShortLoopsOnASingleLine: true
+AllowShortBlocksOnASingleLine: true
+AllowShortFunctionsOnASingleLine: Empty
+AllowShortCaseLabelsOnASingleLine: true
+AllowShortIfStatementsOnASingleLine: AllIfsAndElse
+EmptyLineBeforeAccessModifier: LogicalBlock
+SeparateDefinitionBlocks: Always
+PointerAlignment: Right
+BinPackArguments: false
+BinPackParameters: false
+BreakBeforeBinaryOperators: All
+PackConstructorInitializers: NextLine
+IncludeCategories:
+  - Regex: 'testlib\.h'
+    Priority: 1
+    SortPriority: 0
+    CaseSensitive: false
+  - Regex: '^<(iostream|cstdio)>'
+    Priority: 2
+    SortPriority: 1
+    CaseSensitive: false
+  - Regex: '^<.*'
+    Priority: 2
+    SortPriority: 0
+    CaseSensitive: false
+  - Regex: '.*'
+    Priority: 3
+    SortPriority: 0
+    CaseSensitive: false
+# InsertBraces: true   ## clang-format 15

.prettierignore

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+.vscode

.prettierrc

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+{
+  "tabWidth": 4,
+  "singleQuote": true,
+  "overrides": [
+    {
+      "files": "*.md",
+      "options": {
+        "tabWidth": 2
+      }
+    },
+    {
+      "files": "*.y{,a}ml",
+      "options": {
+        "tabWidth": 2
+      }
+    },
+    {
+      "files": "*.json",
+      "options": {
+        "tabWidth": 2
+      }
+    },
+    {
+      "files": ".prettierrc",
+      "options": {
+        "tabWidth": 2
+      }
+    },
+    {
+      "files": ".clang-format",
+      "options": {
+        "tabWidth": 2
+      }
+    }
+  ]
+}