fix(python-sdk): export matched cluster filter params

[realfishsam]

Summary

• Add a shared MatchedClusterFilterParams TypedDict to the Python SDK.
• Make market/event cluster params inherit that shared filter base and export it from package root.

Fixes #1157

Test Plan

• python3 -m py_compile sdks/python/pmxt/models.py sdks/python/pmxt/__init__.py
• Static AST/export check for MatchedClusterFilterParams inheritance and package-root export
• git diff --check

[realfishsam]

Local scoped validation passed for this PR:

• python3 -m py_compile sdks/python/pmxt/models.py sdks/python/pmxt/__init__.py
• Static AST/export check confirming MatchedClusterFilterParams is defined, exported, and used as the base for market/event cluster params
• git diff --check

Current required generated-sync checks are red, but the failed diffs are broad pre-existing generated drift outside this focused Python type export (client generators would remove hosted-mode client helpers; API reference generation also changes unrelated sourceExchange/exchange docs and removes a TypeScript question doc line). I did not fold that unrelated drift into this focused PR.

[realfishsam]

PR Review: PASS (NOT VERIFIED)

What This Does

Exports a shared Python MatchedClusterFilterParams TypedDict and refactors the market/event matched-cluster params to inherit the shared filter fields. This matters to Python SDK consumers who want to type reusable matched-cluster filter objects rather than only the market/event-specific aliases.

Blast Radius

Python SDK model/export surface only: sdks/python/pmxt/models.py and sdks/python/pmxt/__init__.py. No sidecar, OpenAPI schema, venue normalizer, router, or TypeScript SDK behavior is changed.

Consumer Verification

Before (base branch):
MatchedClusterFilterParams is not exported from pmxt.__init__.

Evidence:

base export name in file: False

After (PR branch):
MatchedClusterFilterParams is imported into the package root and listed in __all__; the market/event params inherit the shared filter annotations.

Evidence:

pr export name in file: True
has MatchedClusterFilterParams True
market has query True
event has query True

Full import pmxt could not be executed in this review environment because the generated Python client package (pmxt_internal) is not present, so this is source/AST-level verification rather than an installed-wheel import check.

Test Results

• Build: N/A (Python type/export-only change)
• Unit tests: PASS (Python AST parse and targeted models.py import)
• Server starts: N/A
• E2E smoke: N/A (not sidecar/API-visible)

Findings

No blocking findings.

PMXT Pipeline Check

• Field propagation (3-layer): N/A
• OpenAPI sync: N/A
• Financial precision: N/A
• Type safety: OK
• Auth safety: N/A

Semver Impact

patch -- Python SDK export/type-alias compatibility fix.

Risk

Not verified from an installed Python package because generated SDK artifacts are unavailable in this checkout; CI/wheel build should still confirm from pmxt import MatchedClusterFilterParams works end-to-end.