feat(portfolio): stamp the producing SDK build in provenance (wiki-advisory F1) [skip-docs]

The advisory finding: provenance.py/artifacts.py stamped no SDK version, while
the SDK's total_cost_usd is a client-side ESTIMATE computed against a price
table frozen when the SDK was built. An untraceable estimate is a figure nobody
can check later, so the run now records which build produced it.

Provenance gains sdk_version: str | None. The value comes from the PRODUCING
CLIENT — getattr(client, "sdk_version", None) — exactly as model and cost_usd
already do, never from importlib.metadata at stamp time. That distinction is
the seam: a run driven by the scripted stand-in used no SDK at all, and
stamping the installed version there would attribute a build to a run that
never touched it (§1). SdkModelClient reads the installed build once from
package metadata (offline: no key, no network); every other client reports
null. A blank string is refused by the schema — null is the one way to say
"not produced by the SDK".

Scope note: this traceability covers OUR run cost only. The savings the
framework recommends are settled by the deterministic validator against the
golden suite, and no SDK estimate touches them.

Two seams, both detach-proven RED:
- make the stamp read importlib.metadata instead of the client → a scripted run
  claims a build it never used → red
- back-fill runs/s10/provenance.json → red

That second guard is the point of the change as much as the first. runs/s10/ is
the byte-frozen record of the ONE live run (2026-07-03), executed before this
field existed; the suite reads it nowhere else, so nothing would have caught a
retro-stamp. Adding a build id to it now would be a guess presented as
provenance. It stays without one, and the README says why.

run_s10.py is deliberately untouched (byte-frozen fasit script), and the field
defaults to None, so every existing caller and artifact shape is unchanged.

603 passed · ruff clean · mypy strict clean · runs/s10/ byte-identical.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MQu2xxwedckjU56byu1aUG

CHANGELOG.md

@@ -39,8 +39,14 @@ reverse-engineering the MAF sibling.
   test.
 - **Knowledge-base recipe** — the documented team process for building the OKF bundles the
   framework reads (`docs/oppskrift-kunnskapsbase.md`), with an honest 1–2 week expectation.
+- **Traceable run cost** — the provenance stamp records which SDK build produced the run,
+  read from the producing client rather than the environment, so the SDK's cost estimate can
+  be traced to the price table that computed it. A run not produced by the SDK reports `null`
+  instead of borrowing the installed version.
 - **The programme's one live model run** (S10) — executed and validated at a documented
-  $0.127514, its four artifacts committed as fixed reference output under `runs/s10/`.
+  $0.127514, its four artifacts committed as fixed reference output under `runs/s10/`. That
+  record is never edited after the fact: it predates the `sdk_version` field and is left
+  without one rather than back-filled with a guess.
 - **Load-bearing tests** — every seam is proven by a test that goes red when the seam is
   detached; the whole suite runs offline, with no API key and no network.