tool: read a row as a dotted capability id (V-452)

scope.domain.action, the shape Hexis has always spoken, derived from the row
rather than stored — a derivation is one place to argue with, a column is
whatever the last person to enable the tool typed. The name stays the primary
key and nothing about lookup or execution changes: this is a way to read the
allowlist, not a second allowlist.

MatchCapability widens one way, so house.lock covers every action on the
locks and nothing narrower can claim a wider pattern.

docs/design.md

@@ -321,6 +321,23 @@ Three rules fall out, and they are the part that was missing:
   policy does not recognise gets the confirm turn. A domain argues its way down
   to running freely; it never has to argue its way up to being gated.
 
+#### Capability ids
+
+A row is also read as a dotted capability id, `scope.domain.action` — the same
+shape Hexis has always spoken, which made the local surface the odd one out
+(Vikunja #452). `homelab.docker.restart`, `house.lock.unlock`,
+`mcp_vikunja.vikunja.delete_task`.
+
+Derived, not stored, for the reason the tier is: a derivation is one place to
+argue with. The name is still the primary key and nothing about lookup or
+execution changed — this is a way to READ the allowlist, not a second one.
+`/tools` groups the enabled rows by `scope.domain` and prints the id and the
+tier beside each, because a flat list stops answering "what can she do to the
+house" somewhere around fifteen rows.
+
+`MatchCapability` widens one way: `house` and `house.lock` both cover
+`house.lock.unlock`, and nothing lets a narrower id claim a wider pattern.
+
 The irreversible tier is refused rather than asked about, because a confirm
 turn would be theatre: everything that proposed the act — an STT guess, a
 router guess, a fuzzy allowlist match — is a guess, and a spoken "да" checks