CommonJS model: minified __esModule marker (!0) and read-only called functions #34

Found in the PR #29 round-14 review. Two smaller gaps in PR #29's handling:

1. F21 __esModule marker only recognises literal true. Minified output (Terser, UglifyJS, minified Babel) writes Object.defineProperty(exports,"__esModule",{value:!0}) or exports.__esModule=!0. With exports.default = load, the file stays modelled, and import load from './m' loses the pre-PR edge to m.js:load. Treat any truthy literal (!0, 1, a non-empty string) as the marker.
2. A called function declaration that only reads module/exports blocks every member. function isMain(){ return require.main === module } isMain(); or function peek(){ return exports.a } peek(); sets capturesExports, which invalidates the exports with 'indirect eval effects' (a blocking reason), so every member answers no-edge. The arrow and callback forms keep their edges. Only writes, or eval reachability, should set it.