docs(design): remove SVG, use PNG logo only

SVG icon is no longer in use. public/logo.png (1024x1024 RGBA) is
the single logo asset. DESIGN.md updated accordingly: SVG snippet
removed, wordmark pattern and <head> references updated to PNG.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

node_modules/fraction.js/fraction.d.mts

@@ -0,0 +1,79 @@
+/**
+ * Interface representing a fraction with numerator and denominator.
+ */
+export interface NumeratorDenominator {
+    n: number | bigint;
+    d: number | bigint;
+}
+
+/**
+ * Type for handling multiple types of input for Fraction operations.
+ */
+export type FractionInput =
+    | Fraction
+    | number
+    | bigint
+    | string
+    | [number | bigint | string, number | bigint | string]
+    | NumeratorDenominator;
+
+/**
+ * Function signature for Fraction operations like add, sub, mul, etc.
+ */
+export type FractionParam = {
+    (numerator: number | bigint, denominator: number | bigint): Fraction;
+    (num: FractionInput): Fraction;
+};
+
+/**
+ * Fraction class representing a rational number with numerator and denominator.
+ */
+declare class Fraction {
+    constructor();
+    constructor(num: FractionInput);
+    constructor(numerator: number | bigint, denominator: number | bigint);
+
+    s: bigint;
+    n: bigint;
+    d: bigint;
+
+    abs(): Fraction;
+    neg(): Fraction;
+
+    add: FractionParam;
+    sub: FractionParam;
+    mul: FractionParam;
+    div: FractionParam;
+    pow: FractionParam;
+    log: FractionParam;
+    gcd: FractionParam;
+    lcm: FractionParam;
+
+    mod(): Fraction;
+    mod(num: FractionInput): Fraction;
+
+    ceil(places?: number): Fraction;
+    floor(places?: number): Fraction;
+    round(places?: number): Fraction;
+    roundTo: FractionParam;
+
+    inverse(): Fraction;
+    simplify(eps?: number): Fraction;
+
+    equals(num: FractionInput): boolean;
+    lt(num: FractionInput): boolean;
+    lte(num: FractionInput): boolean;
+    gt(num: FractionInput): boolean;
+    gte(num: FractionInput): boolean;
+    compare(num: FractionInput): number;
+    divisible(num: FractionInput): boolean;
+
+    valueOf(): number;
+    toString(decimalPlaces?: number): string;
+    toLatex(showMixed?: boolean): string;
+    toFraction(showMixed?: boolean): string;
+    toContinued(): bigint[];
+    clone(): Fraction;
+}
+
+export { Fraction as default, Fraction };