# Step: standard library broadened

Tags `v3-stdlib-broaden`. Suite **112/112** (new `Stdlib2Prog`).

## Added

- **`Math`** — `tan`, `arcsin`, `arccos`, `power` (bound to libm
  `tan`/`asin`/`acos`/`pow`; `arcsin`/`arccos`/`power` are thin
  wrappers so the names stay classic). Existing:
  `sqrt/exp/ln/sin/cos/arctan/abs`, `Pi`, `E`.
- **`Strings`** — `Equal` (content equality) and
  `Pos(pattern, s)` (1-based index of the leftmost occurrence, `0` when
  absent). Existing: `Length/Assign/Concat/Compare/Delete/Append/Copy`.
- **`CharClass`** (new) — ASCII classification: `IsDigit`, `IsUpper`,
  `IsLower`, `IsAlpha`, `IsSpace`.

## Test

`compiler/tests/stdlib2_prog.mod` (`Stdlib2Prog`, exit 42, prints
`stdlib2 n=42`) exercises the new `Math`/`Strings`/`CharClass` surface
alongside `SysIO`.

## Note

The directory rename to `syslib/` was **not** done (kept `stdlib/` and
`runtime/syslib/` as-is).

## Files

`stdlib/{math,strings,charclass}.def/.mod`,
`compiler/tests/stdlib2_prog.mod`, `compiler/run_tests.sh`.