MAS-WP-0005-T02: SCP-2 lower-case resource types (spec v0.1.1)

Grammar, statute schema key pattern, parser (is_resource_type, also used
by statute lint), reference parser, spec 6.1 and a new CHANGELOG. Fixtures
p1-042..045; prop-case-001 Ticket=PR42 is now invalid.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 252470@bnt-lap001
Assistant-Session: ad628c8f-4be2-4979-94c9-76c7ed6f8241

docs/spec-change-proposals.md

@@ -49,8 +49,11 @@ lower-case in the grammar.
 
 **Options:**
 - **(a) recommended:** restrict `resource-type` in the grammar to lower-case
-  ALPHA, DIGIT and `-`. `Ticket=PR42` then parses as an opaque target, which
-  is the safe outcome under §6.1 ("no semantics solely because of `=`").
+  ALPHA, DIGIT and `-`. (Correction during implementation: `Ticket=PR42`
+  does **not** become an opaque target, because opaque targets cannot
+  contain `=`. It becomes a non-canonical address, rejected with
+  `invalid-resource-type` and carried as ordinary email. That is stricter
+  and still safe under §6.1.)
 - (b) keep the grammar and state in §8 that the statute's equivalence policy
   also applies to the type name.