fix(python-sdk): export feed client support types

[realfishsam]

Summary

• Export Python FeedClient support types at the package root: Ticker, Tickers, OHLCV, Market, FeedMarket, and OracleRound.
• Add a public-export regression test for the feed support types.

Fixes #1170

Test Plan

• python3 -m py_compile sdks/python/pmxt/feed_client.py sdks/python/pmxt/__init__.py sdks/python/tests/test_public_exports.py
• AST regression check that the feed support types are imported from feed_client and present in __all__
• git diff --check

Notes

• python3 -m pytest was not available in this cron image (No module named pip / no pytest command), so I ran the equivalent targeted AST assertions directly.
• npm run generate:docs --workspace=pmxt-core produced broad unrelated API reference/config drift, so those generated files were reverted to keep this PR scoped.

[realfishsam]

CI is currently red on generated-sync checks that are unrelated to this focused export fix:

• Verify COMPLIANCE.md is up-to-date
• Verify client.py methods are up-to-date
• Verify client.ts methods are up-to-date
• Verify API_REFERENCE.md files are up-to-date

I reproduced the generator path on a fresh origin/main worktree after #1150 and it wants broad generated drift: remove core/COMPLIANCE.md Hunch rows and strip large hosted client overrides in both SDK clients, plus API reference timestamp/source drift. I am intentionally keeping this PR scoped to #1170 instead of folding that unrelated generated drift into it.

Focused validation passed:

• python3 -m py_compile sdks/python/pmxt/feed_client.py sdks/python/pmxt/__init__.py sdks/python/tests/test_public_exports.py
• direct AST regression check for FeedClient, Ticker, Tickers, OHLCV, Market, FeedMarket, and OracleRound imports + __all__
• git diff --check

[realfishsam]

PR Review: PASS (NOT VERIFIED)

What This Does

Exports feed-client support types (Ticker, Tickers, OHLCV, Market, FeedMarket, OracleRound) from the Python SDK package root and adds the missing aliases in feed_client.py. This matters to Python SDK consumers who want the same top-level typed imports they already get for FeedClient.

Blast Radius

Python SDK package-root exports and feed-client type aliases only: sdks/python/pmxt/__init__.py, sdks/python/pmxt/feed_client.py, and a public-exports test. No core sidecar route, exchange normalizer, OpenAPI schema, TypeScript SDK, or generated SDK code is affected.

Consumer Verification

Before (base branch):
Static consumer-path check on origin/main showed __init__.py did not import/export the support types, and feed_client.py did not define Tickers or FeedMarket.

# origin/main
from pmxt import FeedClient  # available
from pmxt import Ticker, Tickers, FeedMarket  # not available at package root

After (PR branch):
Static consumer-path check on pr-1172 showed __init__.py imports the support types from feed_client and includes them in __all__; feed_client.py defines the new aliases.

from .feed_client import FeedClient, FeedMarket, Market, OHLCV, OracleRound, Ticker, Tickers

Tickers = Dict[str, Ticker]
FeedMarket = Market

Test Results

• Build: N/A — Python export-only source change; python3 -m py_compile sdks/python/pmxt/__init__.py sdks/python/pmxt/feed_client.py passed.
• Unit tests: NOT VERIFIED — repository-level Python pytest is unavailable in this review environment (/usr/bin/python3: No module named pytest observed during the daily verification run), and importing pmxt directly is blocked by absent generated package dependency pmxt_internal in this checkout.
• Server starts: N/A — no sidecar API behavior changed.
• E2E smoke: N/A — no HTTP consumer path changed.

Findings

No blocking findings.

PMXT Pipeline Check

• Field propagation (3-layer): N/A
• OpenAPI sync: N/A
• Financial precision: N/A
• Type safety: OK — aliases point at the existing dataclass/tuple/dict types without changing runtime behavior.
• Auth safety: N/A

Semver Impact

patch -- backward-compatible public export/type-alias fix.

Risk

I could not execute the Python public-export test suite end-to-end because the local review checkout lacks pytest/generated pmxt_internal; verification is based on source inspection plus Python syntax compilation.