chore(issue-forms): retire local templates -> inherit org canon (#25)

Removes this repo's local `.github/ISSUE_TEMPLATE` override so it
inherits the consistent org-wide issue forms from
`hyperpolymath/.github`. The local set was an inferior subset of the
canon (confirmed by the estate issue-template audit). One design
everywhere.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: hyperpolymath