Match the raise-abandons test doubles to the current session signatures

[v-positronic]

main is red at 917111a — both Check code style and Run unit tests fail, on the same two lines.

_BoomSession.__call__ took (obs) and _BoomPolicy.new_session took (context, now, rt). basedpyright rejects both as incompatible overrides, and the harness calls the session with the time, so the test raises TypeError: __call__() takes 2 positional arguments but 3 were given at harness.py:61 on every platform in the matrix.

Why it got in

Neither pull request was wrong on its own.

• Call a policy session with the time, not with a clock #676 changed Session.__call__ to take time_ns and Policy.new_session to take rt.
• Publish the deadline the harness ends the live episode at #662 wrote this test against the signatures as they stood before it, and merged after.

Each was green alone. A type checker only sees an override against its base once both are on one branch, so the pair is red and neither PR's own CI could have caught it.

Scope

Every other double in test_harness.py already uses these signatures. A grep over main for the stale shapes returns these two methods and nothing else:

git grep -nE "def __call__\(self, obs\):" origin/main -- '*.py'
git grep -nE "def new_session\(self.*\bnow\b" origin/main -- '*.py'

Verified

• uv run --locked basedpyright — 0 errors, 0 warnings (was 2 errors)
• uv run --locked pytest positronic/policy/tests/test_harness.py — 78 passed
• ruff check and ruff format --check clean