refactor(jspsych): split recording.ts into a recording/ directory

The single-file `modules/recording.ts` had grown to ~1840 lines holding
schema types, options, internal constants, pure helpers, the global
prototype-patch coordination, and the `SessionRecorder` class itself.
Split into focused siblings under `modules/recording/`:

  index.ts          (32 LOC) — public re-exports
  types.ts         (194 LOC) — schema types only, no runtime
  options.ts        (51 LOC) — RecordSessionOptions + resolver
  constants.ts      (69 LOC) — internal numeric/string constants + CanvasState
  helpers.ts       (162 LOC) — pure utilities (computeDiffBbox, serializeJson, …)
  global-patches.ts (174 LOC) — Math.random / Canvas refcounted patches
  SessionRecorder.ts (1240 LOC) — the main class

The split avoids a circular import between `SessionRecorder` and
`global-patches` by giving the patch module a minimal `RecorderHooks`
interface (`notifyCanvasDraw` + `recordRngCall`) that the concrete
class structurally satisfies.

The public API is unchanged: `import ... from "./modules/recording"`
(or `from "jspsych"`) resolves to `index.ts` which re-exports
everything that was exported from the monolith. Tests + JsPsych.ts
needed no import-path changes.

All 728 workspace tests pass; tsc clean.

Author: claude