chore: rename memory-bank-template to template/memory-bank

[dapi]

Context

The repository currently keeps the upstream payload in memory-bank-template/. After moving repository-level helpers under template/, align the payload location by renaming it to template/memory-bank/.

Scope

• Move memory-bank-template/ to template/memory-bank/ with history-preserving Git renames where possible.
• Update repository documentation, scripts, configuration, and internal links that reference memory-bank-template/.
• Preserve the downstream installation contract: the installed directory remains memory-bank/.
• Update validation commands and CI references for the new source path.

Acceptance criteria

• No active repository references to memory-bank-template/ remain, except migration/history notes if intentionally added.
• Template documentation and relative links resolve from template/memory-bank/.
• memory-bank-cli lint and memory-bank-cli doctor --profile template pass against the renamed template.
• git diff --check passes.