refactor: rename upstream payload to memory-bank-template

[dapi]

Summary

• rename the source payload directory from memory-bank/ to memory-bank-template/ without retaining an upstream compatibility copy
• update source-repository links, contributor instructions, dependency maps, and brownfield/greenfield adoption guidance
• preserve memory-bank/ as the downstream install, lock, navigation, and agent-routing path
• extend template CI with source-layout assertions and a downstream init smoke test

Source and downstream contract

The source checkout now owns memory-bank-template/. A compatible memory-bank-cli release must translate that payload to downstream memory-bank/ for init and update; downstream documentation and lock paths intentionally remain unchanged.

Validation

• git diff --check
• CI workflow YAML parse
• source-repository relative Markdown link check
• source layout assertion: memory-bank-template/ exists and upstream memory-bank/ does not
• downstream copy smoke check: install the payload as memory-bank/ and run memory-bank-cli v1.0.0 lint — PASS across 96 Markdown files

Dependency gate

Draft and merge-blocked by dapi/memory-bank-cli#14. The current released CLI v1.0.0 still inspects upstream memory-bank/, so source lint and template-profile doctor fail as expected after this rename. Before this PR can become ready or merge:

1. release the CLI implementation for refactor: read memory-bank-template source payload while preserving downstream memory-bank memory-bank-cli#14
2. pin that release and checksum in .github/workflows/ci.yml
3. confirm source lint, auto/template doctor, and downstream init smoke checks are green

Closes #63