types: generate TypeScript from engine structs with tygo

tygo is pinned via go.mod's tool directive (Go 1.24+): the tool's
version is locked like any dependency and runs as 'go tool tygo', no
global install. 'go generate ./...' regenerates web/src/types/engine.ts
from Config/Result and their json tags; the generated file is committed
so the frontend builds without Go installed. The go:generate directive
anchors in a root generate.go because generate runs commands from the
declaring file's directory and tygo reads tygo.yaml from the cwd.
go.mod's ignore directive (Go 1.25+) keeps ./... from crawling into
web/node_modules, where some npm packages ship stray .go files.

web/src/types/engine.ts

@@ -0,0 +1,40 @@
+// Code generated by tygo. DO NOT EDIT.
+
+//////////
+// source: scenario.go
+
+/**
+ * Strategy selects who gets educated.
+ */
+export type Strategy = string;
+export const StrategyNone: Strategy = "none";
+export const StrategyRandom: Strategy = "random";
+export const StrategyMostConnected: Strategy = "most-connected";
+/**
+ * Config fully describes one simulation world. It is the single source of
+ * truth for parameters: API and frontend types will be generated from the
+ * structs in this file, never redefined by hand. Identical configs produce
+ * identical results; all randomness flows from the three seeds.
+ */
+export interface Config {
+  numStudents: number /* int */;
+  edgesPerNode: number /* int */; // attachment edges per new student (network density)
+  triangleProb: number /* float64 */; // chance to close a friend-of-a-friend triangle
+  forwardProb: number /* float64 */; // chance a student forwards the fake along an edge
+  numEducated: number /* int */; // students the education program reaches
+  origin: number /* int */; // student who first posts the fake
+  graphSeed: number /* uint64 */;
+  thresholdSeed: number /* uint64 */;
+  educationSeed: number /* uint64 */; // used by the random strategy only
+}
+/**
+ * Result is the outcome of one scenario run.
+ */
+export interface Result {
+  strategy: Strategy;
+  educated: number /* int */[];
+  reachedAtRound: number /* int */[]; // per node; -1 means never reached
+  numReached: number /* int */;
+  numRounds: number /* int */;
+  reachedPct: number /* float64 */;
+}