render: deduplicate footer links against inline references

Render now detects neighbor keys that already appear in the node's
content and omits them from the footer link list. Inline references
serve as the node's own navigation structure; the footer catches
only neighbors not mentioned in prose.

Also fixes PEG query parser to accept hyphens in field names
(content-len was rejected).

memory-instructions-core updated to v12: documents canonical inline
link format (→ `key`), adds note about normalizing references when
updating nodes, and guidance on splitting oversized nodes.

Content is never modified for display — render is round-trippable.
Agents can read rendered output and write it back without artifacts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

poc-memory/src/query/parser.rs

@@ -129,7 +129,7 @@ peg::parser! {
             = "WHERE" _ e:expr() { e }
 
         rule field() -> String
-            = s:$(['a'..='z' | 'A'..='Z' | '_']['a'..='z' | 'A'..='Z' | '0'..='9' | '_']*) {
+            = s:$(['a'..='z' | 'A'..='Z' | '_']['a'..='z' | 'A'..='Z' | '0'..='9' | '_' | '-']*) {
                 s.to_string()
             }