fix(sdk): compute detailed execution prices locally

[realfishsam]

Summary

• Make TypeScript getExecutionPriceDetailed a synchronous local order-book walk instead of a sidecar HTTP call.
• Make Python get_execution_price_detailed compute the same pure result locally.
• Add focused TS/Python regressions for full and partial fills with sidecar autostart disabled.

Fixes #1306

Test Plan

• git diff --check HEAD~1..HEAD ✅
• node sdks/typescript/scripts/generate-client-methods.js ✅
• node sdks/python/scripts/generate-client-methods.js ✅
• npm test --workspace=pmxtjs -- --runTestsByPath tests/execution-price-detailed-local.test.ts --runInBand blocked locally: this checkout lacks sdks/typescript/generated/src/index.js; npm run generate --workspace=pmxtjs is blocked by missing java in the cron environment.
• PYTHONPATH=sdks/python python3 sdks/python/tests/test_execution_price_detailed_local.py blocked locally: this checkout lacks generated pmxt_internal.

[realfishsam]

PR Review: PASS (NOT VERIFIED)

What This Does

Moves get_execution_price_detailed calculation into the Python and TypeScript SDK clients so consumers can compute detailed fill price from a supplied OrderBook without calling the sidecar-only getExecutionPriceDetailed route.

Blast Radius

Python SDK Exchange.get_execution_price_detailed, TypeScript SDK Exchange.getExecutionPriceDetailed, and their local unit-test coverage. No core exchange normalizer/OpenAPI schema changes.

Consumer Verification

Before (base branch):
The SDK method builds a sidecar request to POST /api/{exchange}/getExecutionPriceDetailed with the order book, side, and amount; consumer behavior depends on a running sidecar route.

Polymarket(auto_start_server=False).get_execution_price_detailed(order_book, "buy", 8)
# base implementation attempts sidecar HTTP POST /api/polymarket/getExecutionPriceDetailed

After (PR branch):
Static review of sdks/python/pmxt/client.py and sdks/typescript/pmxt/client.ts shows the method now walks asks for buys and bids for sells, sorts the book side by best execution price, returns partial-fill metadata, and raises on non-positive amount. Example from the added tests:

asks=[(0.52, 4), (0.50, 6)], side="buy", amount=8
# fills 6 @ 0.50 + 2 @ 0.52 => price 0.505, filled_amount=8, fully_filled=True

Runtime SDK verification was blocked by missing generated SDK artifacts in this checkout, not by this PR's changed logic.

Test Results

• Build: PASS (npm run build --workspace=pmxt-core)
• Unit tests: NOT VERIFIED for SDK tests. npx jest -c sdks/typescript/jest.config.cjs sdks/typescript/tests/execution-price-detailed-local.test.ts --runInBand fails before tests run with TS2307: Cannot find module '../generated/src/index.js'; uv run pytest tests/test_execution_price_detailed_local.py -q fails dependency resolution because project requires-python >=3.8 conflicts with urllib3>=2.7.0 requiring Python >=3.10 for the Python 3.9 split.
• Server starts: NOT RUN (SDK-local behavior change; core build passed)
• E2E smoke: NOT VERIFIED (not sidecar-observable after the change)

Findings

No blocking findings.

PMXT Pipeline Check

• Field propagation (3-layer): N/A
• OpenAPI sync: N/A
• Financial precision: OK for existing SDK numeric model; no new float-sensitive venue/API serialization path added.
• Type safety: OK in changed hand-written code; SDK generated-import blocker prevented full TS test execution.
• Auth safety: N/A

Semver Impact

patch -- SDK-local bug fix/removal of unnecessary sidecar dependency for an existing helper method.

Risk

The old TypeScript getExecutionPrice helper still walks order-book levels in caller-supplied order, while the new detailed method sorts best-first. That is outside this PR's direct change but means the two helpers can disagree if consumers pass an unsorted book. Full SDK test execution remains unverified until generated artifacts/dependency resolution are available.