fix(python-sdk): accept wallet address in Hunch client

[realfishsam]

Summary

• Add wallet_address to the Python Hunch convenience client constructor.
• Forward the value to the shared Exchange base class so hosted-mode reads/writes can resolve wallet-scoped endpoints.
• Add a regression covering the Hunch constructor.

Fixes #1372

Test Plan

• python3 -m py_compile sdks/python/pmxt/_exchanges.py sdks/python/tests/test_hosted_dispatch.py
• PYTHONPATH=/tmp/pmxt-pystub:sdks/python python3 -m pytest sdks/python/tests/test_hosted_dispatch.py::test_hunch_constructor_accepts_wallet_address_for_hosted_mode -q

Note: the local checkout lacks committed generated pmxt_internal artifacts, so the focused pytest used an untracked /tmp/pmxt-pystub generated-client stub only for importability.

[realfishsam]

PR Review: FAIL

What This Does

This attempts to let Python SDK consumers construct Hunch(pmxt_api_key=..., wallet_address=...) so hosted Hunch wallet-scoped calls can carry the wallet address through the shared Exchange base class.

Blast Radius

Python SDK exchange wrapper generation only: sdks/python/pmxt/_exchanges.py and the hosted dispatch test file. This affects the public Python Hunch constructor; no core sidecar exchange logic or OpenAPI schemas are changed.

Consumer Verification

Before (base branch):
Static constructor inspection of origin/main:sdks/python/pmxt/_exchanges.py shows Hunch.__init__ has no wallet_address kwarg:

base False ['self', 'private_key', 'base_url', 'auto_start_server', 'pmxt_api_key']

A Python SDK consumer passing wallet_address= would therefore hit TypeError: Hunch.__init__() got an unexpected keyword argument 'wallet_address'.

After (PR branch):
Static constructor inspection of pr-1376-review:sdks/python/pmxt/_exchanges.py shows the PR adds the kwarg:

pr True ['self', 'private_key', 'base_url', 'auto_start_server', 'pmxt_api_key', 'wallet_address']

However, the file header says _exchanges.py is generated and must not be edited manually. I ran the declared generator path on the PR worktree:

npm run generate:python-exchanges --workspace=pmxt-core

The regenerated diff removes the new Hunch wallet_address kwarg again:

@@ class Hunch(Exchange):
-        wallet_address: Optional[str] = None,
@@
-            wallet_address: EVM wallet address used for hosted reads/writes
@@
-            wallet_address=wallet_address,

So the consumer-visible fix is not durable: any normal SDK regeneration will drop it.

Test Results

• Build: NOT VERIFIED for full SDK; not needed to demonstrate the generator regression.
• Unit tests: NOT VERIFIED; direct Python import in this worktree is blocked by missing local generated pmxt_internal, but AST/generator checks are sufficient for the blocking generated-file issue.
• Server starts: N/A (constructor-only Python SDK wrapper change).
• E2E smoke: N/A (no sidecar behavior changed).

Findings

1. sdks/python/pmxt/_exchanges.py:1 / sdks/python/pmxt/_exchanges.py:545 — blocking generated-file edit. The PR changes _exchanges.py directly, but its header states it is generated from core/scripts/generate-python-exchanges.js. Running the generator on the PR removes the new Hunch wallet_address constructor parameter, so the fix will be silently lost during the next SDK regeneration/release. The durable fix needs to update the generator/source-of-truth (for example an override for Hunch hosted wallet params) and commit the regenerated output.

PMXT Pipeline Check

• Field propagation (3-layer): N/A
• OpenAPI sync: N/A
• Financial precision: N/A
• Type safety: ISSUE — public constructor surface is only present in generated output, not in its generator/source of truth.
• Auth safety: OK — no credentials are logged/exposed by this change.

Semver Impact

patch -- intended Python SDK constructor compatibility fix.

Risk

Until the generator/source-of-truth is updated, the Hunch hosted wallet-address support can disappear during routine SDK generation, causing the same consumer wallet_address constructor failure to recur.