test(auth): pin the fail-closed Bearer-scope contract

Four structural guards freeze the invariants the change rests on: the set of
files that can resolve a Bearer token to a user, the single deliberate
any-valid-token posture, the mint sites with their scope sets, and the rule
that a declared scope is an exported constant rather than a literal.

Thirteen behavioural cases run against a real Postgres and the real resolver.
Four of them go red on the pre-fix tree — a narrow token reading the
full-backup export and the labs surface, and an MCP token on a REST read.
The rest pin the flows that must NOT change: the per-medication ingest pair
still works, the token without the per-medication grant is still refused, a
wildcard token still reaches the export and the batch ingest, an MCP token
still resolves on /mcp with its write scope intact, a declared fhir:read
still opens the FHIR face and nothing else, cookie sessions are unaffected,
and requireAdmin still refuses a wildcard Bearer.

The workout-batch case that asserted narrow tokens are admitted claimed the
iOS sync depended on it. It does not: workouts:ingest has no mint site
anywhere, and iOS holds a ["*"] token. Replaced with a case that asserts both
halves of the real contract.

Documentation updated for the enforcement rule and the retired mint.

docs/self-hosting/mcp.md

@@ -65,10 +65,10 @@ Still in **Settings → MCP → Tokens**:
 3. **Copy the `hlk_…` value now** — it is shown exactly once and cannot
    be retrieved again. Tokens default to a 90-day lifetime.
 
-The token never carries the `*` wildcard and never the
-`medication:ingest` scope the generic `/api/tokens` mints — it is the
-least-privilege MCP scope and nothing more. The same list shows
-last-used time and lets you revoke any token.
+The token never carries the `*` wildcard and never a medication-ingest
+scope — it is the least-privilege MCP scope and nothing more, and it is
+bound to the MCP surface: it is refused on every REST route. The same
+list shows last-used time and lets you revoke any token.
 
 Cloud connectors that use OAuth (next section) mint the same
 `health:read` scope automatically, so for Claude.ai / ChatGPT you do not