fix: inclusive date bounds, UTC conversions, and Massive aggregate pagination

[quantum-like]

Owning issue

Closes #73

Outcome

7 correctness fixes, one commit each, each with a focused test:

• Fama-French YYYY-MM end filters used day 28, so daily/weekly rows on the 29th–31st were dropped. They now use the real month end. Test: tests/test_fama_french_provider.py::test_fetch_month_filter_includes_final_calendar_day. (3a942fc)
• Storage gap detection passed an inclusive end into an exclusive read, so a complete series reported a one-day gap on the end date. The end bar is now included. Test: tests/test_update_manager.py::test_detect_gaps_in_storage_keeps_bar_on_inclusive_end. (9825551)
• The macro yfinance fallback omitted the configured end date because Yahoo's end is exclusive. It now requests the next day. Test: updated assertion in tests/test_macro_downloader.py. (b062fa5)
• Finnhub date bounds were converted in local time and a date-only end dropped that day's bars. Bounds are now UTC, with the end at 23:59:59 UTC. Test: tests/test_finnhub_provider.py::test_fetch_raw_data_uses_inclusive_utc_day. (9501712)
• Kalshi candlestick bounds were converted in local time. They are now UTC. Test: tests/test_kalshi_unit.py::test_fetch_raw_data_uses_utc_calendar_bounds. (d4a4008)
• Polymarket price-history bounds were converted in local time. They are now UTC. Test: tests/test_polymarket_unit.py::test_fetch_price_history_uses_utc_day_bounds. (55f6523)
• Massive aggregate fetches (providers/polygon.py) returned only the first 50,000-row page, silently truncating long minute history. They now follow next_url. Test: tests/test_polygon_provider.py::test_fetch_raw_data_follows_next_url. (e09a0e8)

Compatibility

• No public compatibility impact
• Compatibility impact is documented in the owning issue and migration guidance

Requests now include the configured end date and use UTC day bounds, so results can contain bars that were previously dropped; long Massive histories return all pages.

Verification

• Tests reproduce the prior failure or verify the requested behavior (each listed test fails on main and passes with its fix)
• Ruff lint and format checks pass (ruff format --check is clean on the changed files and ruff check reports nothing new in them versus main, but I did not run the full pre-commit suite)
• ty passes (not run on this branch)
• Test suite passes: Offline pytest tests -q -ra: 3656 passed before, 3662 passed after (283 network, paid-tier and credentialed tests deselected both times). The 7 touched modules also pass under TZ=America/New_York (293 passed). Integration, paid-tier and credentialed tests were not run.
• Package build passes when applicable (not run)
• Strict MkDocs build passes when documentation is affected (no documentation changes)
• Ecosystem qualification passes (not run)

Documentation and release

No documentation changes. The behavior changes above may be worth a line in the next patch-release notes.

Amir