CB-WP-0006 T04: withdraw AM-4c; and fix where AM-6 is measured

AM-4c is withdrawn from the acceptance table and retained as a reported
diagnostic. GameKernel §5a carries the argument.

The ratio has no monotone better direction. INTENT's rule is "own the
semantics, assimilate the implementation": rising can mean owning
semantics properly or reimplementing what should have been assimilated;
falling can mean leverage or dependency bloat. A target requires knowing
which way is better. It is also redundant — AM-4a/AM-4b bound the
denominator and AM-2 bounds own-source density, so AM-4c is a ratio of two
already-targeted quantities.

Measured at withdrawal: 1,426 own lines per 100k third-party (shipped),
1,107 (dev). make dep-weight now prints both, labelled diagnostic — the
row was never actually reported before.

M-D1-MUT keeps AM-4c in its denominator on purpose and says so in the
output. Dropping it would move the score 7/14 -> 7/13 without enforcing
anything: a score improved by deleting the question.

Decided before Phase B deliberately, since ADR-0005 predicts own-source
growth that will move this ratio; deciding after would be the retarget
§Step 4 forbids.

A T01 correction found here. The AM-6 gate failed inside `make all` at
38,753 ev/s against 341,280 in isolation — a 9x drop, because cargo test
runs binaries and threads concurrently. A throughput assertion inside a
parallel harness measures contention, not throughput. T01's measurement
was valid; its gate placement was not.

Fixed by running it only where valid — #[ignore] plus `make am6` in
release with --test-threads=1, now 2.0M ev/s at 20.2x headroom — and not
by lowering the target, which T01 forbade. My first attempt did drift that
way, adding a debug "sanity floor" of 50,000, and was backed out: a second
threshold is still a second chance to tune.

The mutation then went SURVIVED on the first run after the move. 4,000
black_box iterations were calibrated against debug's 3.4x headroom and are
invisible against release's 20x. Raised to 100,000; back to red. A weak
mutation is not a fixed property of a row — it can become weak when the
row's measurement conditions change.

Tier S (amends one row, creates no capability), chaos d4=2, no override.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/dep-weight.py

@@ -186,6 +186,14 @@ def main():
                 f"{r['third_party_loc']:>9,} lines third-party  "
                 f"[{mark} target {limit:,}]"
             )
+        # AM-4c: own source per 100k third-party lines. A DIAGNOSTIC, not a
+        # target — see specs/GameKernel.md §5 and CB-WP-0006 T04. The ratio
+        # has no monotone better direction, so it cannot carry a threshold.
+        for label in CONFIGS:
+            tp = report[label]["third_party_loc"]
+            if tp:
+                print(f"  AM-4c {label:<18}{own / (tp / 100_000):>9,.0f} own "
+                      f"lines per 100k third-party   (diagnostic, not targeted)")
         delta = (
             report["dev-toolchain"]["third_party_loc"]
             - report["shipped-runtime"]["third_party_loc"]