chore(a2ml): remove 8 deprecated legacy-Scheme example dups (Item 10)

Orthogonal cleanup slice of Item 10 (not the STATE v2 conversion
workstream in #77/modshells#43). The agentic/meta/neurosym/playbook
example dirs each carried {minimal,comprehensive}.scm that self-declare
"DEPRECATED ... legacy Guile Scheme (.scm) format" and point at their
already-present, verified .a2ml siblings.

Delete the 8 deprecated .scm dups and repoint the only in-repo refs --
the meta-a2ml and playbook-a2ml README.adoc example link lists --
from examples/*.scm to examples/*.a2ml so no doc links break.
PRESERVE policy unchanged (guix/channels/manifest, tree-sitter,
(define-module) Guile, .scm-suffixed satellite paths untouched).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: hyperpolymath

agentic-a2ml/examples/comprehensive.scm

@@ -213,8 +213,8 @@ The formal specification is in the `spec/` directory:
 
 See the link:examples/[examples/] directory:
 
-* link:examples/minimal.scm[minimal.scm] - Minimal valid META file
-* link:examples/comprehensive.scm[comprehensive.scm] - Full-featured example
+* link:examples/minimal.a2ml[minimal.a2ml] - Minimal valid META file
+* link:examples/comprehensive.a2ml[comprehensive.a2ml] - Full-featured example
 
 == Integration with STATE.a2ml