fix(codeowners): substitute the un-instantiated {{OWNER}} placeholder (#44)

CODEOWNERS carried the literal `@{{OWNER}}`. GitHub's own validator
reports every such rule as **Invalid owner**, so the file assigns **no
code owners at all** — and any ruleset with `require_code_owner_review`
becomes **unsatisfiable**.

`just init` does a repo-wide brace-token substitution and simply never
ran here. Measured estate-wide: **54 repos** carried it; **2 are genuine
templates** where the placeholder is correct and are deliberately
untouched.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: hyperpolymath

.github/CODEOWNERS

@@ -2,13 +2,13 @@
 # CODEOWNERS - Define code review assignments
 # See: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners
 #
-# Replace {{OWNER}} with your GitHub username or team
+# Replace hyperpolymath with your GitHub username or team
 
 # Default owners for everything
-* @{{OWNER}}
+* @hyperpolymath
 
 # Security-sensitive files require explicit review
-SECURITY.md @{{OWNER}}
-.github/workflows/ @{{OWNER}}
-Trustfile.a2ml @{{OWNER}}
-.machine_readable/ @{{OWNER}}
+SECURITY.md @hyperpolymath
+.github/workflows/ @hyperpolymath
+Trustfile.a2ml @hyperpolymath
+.machine_readable/ @hyperpolymath