[ketpatil77]

Fixes #876.

Add massive/py.typed to the current package namespace. The project has renamed polygon to massive; this exposes the existing Massive annotations without introducing or restoring a polygon package.

Validation on Windows / Python 3.11.9:

• Original source and wheel artifacts lack massive/py.typed. Verified the corrected sdist, direct wheel, and wheel rebuilt from the extracted sdist all retain the empty marker at the correct package path. In separate installed-wheel environments outside the checkout, mypy 2.4.0 reports import-untyped before the fix; the valid consumer probe passes after the fix and a deliberately invalid consumer is rejected. These focused probes use follow_imports=silent and suppress missing dependency imports; they do not assert that the entire library is strict-type-check clean.
• Request-option/model subset: 4 passed, 1 failed. The exact header-dictionary expectation (User-Agent/version fallback and Accept-Encoding) also fails with the unchanged baseline wheel. Windows cannot check out two overlong fixture filenames, so validation used a sparse checkout; the complete REST/WebSocket suite, full lint, and whole-SDK mypy check were not run. No live API requests were made.
• git diff --cached --check passes.

Runtime implementations and test expectations are unchanged.