docs: where we stand -- capability, approach, ax integration, token economics, open items

One page, docs/where-we-stand.md, composed with the COBESY composition method (governing idea,
SCQA opener, MECE sections): the M4 gates and the state against them, the detection approach step
by step, ax on the server, token economics before and after, and the open items. Every figure is
quoted from a committed record whose path stands next to it.

decision-engine.md, evaluation.md and token-ergonomics.md link to the page where they repeated its
content (detail tables kept); decision-engine.md's Experiments section now records exp-002's
result instead of saying it has not run. Linked from the nav, the index and the README.

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

docs/evaluation.md

@@ -112,10 +112,10 @@ gate: at least 16 of 20 declared sites agreed, at a cost per candidate under $0.
 
 ## The decision engine
 
-Two slices of the learned decision engine have been measured out of repository: injection alone
-(2026-10-01) and the six evaluable families (2026-10-02: pooled AUC 0.77 to 0.96 per family,
-within-pair AUC 0.72 to 0.93, BLOCK offered for none). The numbers and their records are in
-[decision-engine.md](decision-engine.md). The engine is not adopted.
+Two slices have been measured out of repository (injection, 2026-10-01; six families,
+2026-10-02). The engine is not adopted. The state against the gates, in one place with the plane
+increment and the populations above, is on [Where we stand](where-we-stand.md#1-detection-capability-and-goals-no-go-measured);
+the per-family tables are on [decision-engine.md](decision-engine.md).
 
 ## Removal of the earlier agentic extra