spec: note jolt's unknown-alias behavior; corpus rows for the reader/edn fixes

The EBNF and reader S7 already specified ::kw auto-resolution — the
implementation was out of spec, now aligned. S7 noted unknown ::alias/k MUST be a
read error; jolt is lenient (reads :alias/k), so record that as a deviation.
Corpus gains JVM-certified rows for ::kw resolution, clojure.edn :default
receiving a symbol tag, and with-meta on a lazy seq.

docs/spec/02-reader.md

@@ -59,8 +59,9 @@ keyword  := ':' name | ':' ns '/' name | '::' name | '::' alias '/' name
   . $ & %` (with `%` and `&` further constrained inside `#()`); a symbol
   MUST NOT begin with a digit; `.` and `/` have positional restrictions.
 - S7. `::kw` MUST resolve to the current namespace at *read* time
-  (`::k` in ns `user` reads as `:user/k`); `::alias/k` resolves the alias or
-  MUST be a read error if the alias does not exist.
+  (`::k` in ns `user` reads as `:user/k`); `::alias/k` resolves `alias` through
+  the current namespace's aliases. (Clojure raises a read error for an unknown
+  alias; jolt reads it as `:alias/k`.)
 
 ### Strings and characters