FIX/strike_limit typed as float causes API requests to fail

[MarketDataDev03]

Fix: strike_limit typed as float causes API requests to fail

Closes #24

Summary

options.chain(..., strike_limit=10) failed because strike_limit was annotated
as float | None. Pydantic (lax mode) coerced the integer 10 to 10.0, which
was then serialized into the request URL as strikeLimit=10.0 — a value the API
rejects, since strike_limit is a count of strikes, not a price.

This PR changes the field's type to int | None so integer inputs stay integers
on the wire, and updates the documentation accordingly.

Problem

client.options.chain(symbol="AAPL", strike_limit=10)
# → request URL: .../options/chain/AAPL/?...&strikeLimit=10.0
# → API rejects the request

Root cause — src/marketdata/input_types/options.py:67:

strike_limit: float | None = Field(
    description="The strike limit to filter by", alias="strikeLimit", default=None
)

Changes

src/marketdata/input_types/options.py

-    strike_limit: float | None = Field(
+    strike_limit: int | None = Field(
         description="The strike limit to filter by", alias="strikeLimit", default=None
     )

With int | None, Pydantic keeps 10 as 10, and _build_url serializes it
into strikeLimit=10.

docs/options.md

-- `strike_limit` (float, optional): Limit the number of strikes
+- `strike_limit` (int, optional): Limit the number of strikes

Testing

Two new tests in src/tests/test_options_chain.py, covering the bug at two
levels:

• test_options_chain_input_strike_limit_typed_as_int — unit test on the
  input model. Asserts that OptionsChainInput(strike_limit=10).strike_limit is
  kept as an int (type(...) is int), not coerced to a float.
• test_options_chain_strike_limit_is_int_on_wire — integration test that
  inspects the actual outgoing request via
  respx_mock.calls.last.request.url.params and asserts
  params["strikeLimit"] == "10" (not "10.0"). Mirrors the existing
  test_options_chain_input_date_range_aliases_on_wire pattern.

Developed with a TDD red → green cycle.

297 passed

Full suite green — no regressions.

Files changed

File	Change
src/marketdata/input_types/options.py	strike_limit retyped float | None → int | None
docs/options.md	Documented type updated to int
src/tests/test_options_chain.py	2 new regression tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (fb1ea8e) to head (a986efd).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #28   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           52        52           
  Lines         2281      2281           
=========================================
  Hits          2281      2281           

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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