fix(types): declare input_hash/output_hash on ReceiptPayload

[web3guru888]

fix(types): declare input_hash/output_hash on ReceiptPayload

What

In proof_only mode ReceiptBuilder.build redacts inputs/output to None
and adds input_hash/output_hash SHA-256 digests
(src/aevs/core/receipt.py:137-139):

if cfg.receipt_visibility == "proof_only":
    receipt["input_hash"] = input_hash
    receipt["output_hash"] = output_hash

…but those two keys were absent from the ReceiptPayload TypedDict
(src/aevs/core/types.py). Type checkers therefore could not see the keys a
proof_only receipt actually carries, and the gap was masked behind a
# type: ignore[return-value] on the return statement.

The fix

Declare both keys as optional schema members:

class ReceiptPayload(_ReceiptRequired, total=False):
    input_hash: str
    output_hash: str

They are optional because only proof_only receipts carry them — private
and public receipts omit them entirely.

Why the TypedDict-inheritance idiom (not NotRequired)

The project targets python = "^3.10". typing.NotRequired is 3.11+, and
typing_extensions is not a declared dependency. The native, dependency-free
way to express per-key optionality on 3.10 is a required base TypedDict plus a
total=False subclass — which is what this PR uses. ReceiptPayload remains
the single public name.

About the # type: ignore[return-value] — a finding

The ignore did not stem from the missing keys. The receipt is built
incrementally as a dict[str, Any] (so the conditional proof_only keys and the
post-hoc payload_hmac can be appended), and mypy rejects returning a
dict[str, Any] where a TypedDict is expected:

src/aevs/core/receipt.py:162: error: Incompatible return value type
    (got "dict[str, Any]", expected "ReceiptPayload")  [return-value]

So simply deleting the comment re-surfaces that error (see
01-ignore-is-load-bearing-on-main.txt). It is replaced with an explicit,
type-checked cast(ReceiptPayload, receipt) — a typed boundary assertion at
the end of the builder rather than a blanket line-level error suppression. The
signing/chain bytes are unchanged: the dict is still canonicalized and
signed without payload_hmac exactly as before, so existing signature/chain
tests continue to pass byte-for-byte.

Tests

New tests/test_receipt.py::TestReceiptPayloadSchema (5 cases):

Test	Asserts
test_hash_fields_are_optional_schema_keys	input_hash/output_hash ∈ __optional_keys__
test_hash_fields_are_not_required	…and ∉ __required_keys__
test_builder_keys_are_declared_in_schema	every key a proof_only receipt emits is declared
test_proof_only_emits_the_optional_keys	proof_only receipts carry both keys
test_default_visibility_omits_optional_keys	private receipts omit both keys

The first and third fail on main (keys absent from the schema); all pass with
this change (see 02-schema-tests-fail-before-fix.txt).

Verification (make check)

• pytest: 497 passed, 2 skipped (492 baseline + 5 new) — 03-full-suite.txt
• ruff check: clean — 04-ruff.txt
• mypy --strict: clean, 22 files — 05-mypy.txt

Note: the full suite requires the declared dev-deps (langgraph,
pytest-asyncio in [tool.poetry.group.dev.dependencies]) installed; with
only the langchain,mcp extras, tests/test_invocation_id.py errors on
import langgraph — an environment quirk unrelated to this change.

Closes the type-checker blind spot for proof_only receipts.