docs: state the authority adapter claim precisely

"The adapter itself is NOT IN TREE" was too strong and it was wrong. An adapter
does ship: Trinity.Authority.Local. Grepping the behaviour resolves two files,
lib/trinity/authority/local.ex and a test fixture at
test/support/authority/adapters.ex.

Corrected to: the seam is in the tree, selection happens once at boot from
TRINITY_AUTHORITY, one implementation ships and it is Local, and no adapter
other than Local ships in this tree. An external authority adapter lives in
another repository and nothing in mix.exs or mix.lock depends on one, which an
assessor can confirm from the dependency list rather than from the page.

Checked while correcting it: the only occurrence of the platform name anywhere
in mix.exs, mix.lock, config/ or lib/ is the forbidden-name list inside the name
check that exists to fail the build if such a name appears. Not a dependency.

The parallel claim about the key seam holds unchanged: one implementation of
Trinity.Keys, lib/trinity/keys/local.ex, so no KMS or HSM adapter is in the tree.

README gains one sentence: this pack documents the gap; it does not close it.

Signed-off-by: Ayla Croft <aylacroft@proton.me>

Author: HackTuah

docs/regulated/README.md

@@ -69,3 +69,5 @@ model prompt and what may not. Read both before the others.
 This directory is documentation only. It adds no code, changes no behaviour, and asserts no control
 that is not already in the tree. Where the tree does not implement something this pack names, the
 row says **NOT IN TREE** rather than describing an intention.
+
+This pack documents the gap; it does not close it.

docs/regulated/authorization-boundary.md

@@ -74,10 +74,20 @@ keeps **no executor** for the effects that adapter governs, and that absence is
 over the tree rather than by intent (`lib/trinity/authority.ex`, and the census recorded in slice
 027's record).
 
-The adapter itself is **NOT IN TREE**. ADR-0008 (`docs/adr/0008-authority-is-an-adapter.md`) states
-that no slice in this repository builds one and that it is downstream work in a downstream
-repository. An assessor evaluating a regulated deployment is evaluating that adapter as well as
-this software, and this pack says nothing about it.
+**Stated precisely, because the loose version of this sentence is wrong.** The seam is in the tree:
+`lib/trinity/authority.ex` is the behaviour, and `lib/trinity/authority/selection.ex` picks an
+implementation once at boot from `TRINITY_AUTHORITY` (ADR-0010). **One implementation ships here,
+and only one:** `Trinity.Authority.Local` (`lib/trinity/authority/local.ex`), which is the sole
+module in the tree that calls a tool's `execute/2` for an effectful tool. Grepping the behaviour
+resolves two files and the second is a test fixture (`test/support/authority/adapters.ex`).
+
+**No adapter other than `Local` ships in this tree.** An external authority adapter is a module in
+another repository, and ADR-0008 (`docs/adr/0008-authority-is-an-adapter.md`) states that no slice
+in this repository builds one. Nothing in `mix.exs` or `mix.lock` depends on one; an assessor can
+confirm that from the dependency list rather than from this page.
+
+An assessor evaluating a regulated deployment is evaluating that adapter as well as this software,
+and this pack says nothing about it.
 
 ## What crosses the boundary, and when