Add optional tags or scopes to Remember entries

[bponghneng]

Goal

Make larger memory files easier to scan and retrieve by adding optional tags/scopes.

Proposed Scope

• Evaluate a lightweight Tags or Scope field for curated memory entries.
• Support repo, subsystem, language, tool, or workflow scopes.
• Update templates and review guidance without overcomplicating small projects.

Value

Improves retrieval when .remember/MEMORY.md grows across multiple repos, tools, or domains.

Acceptance Criteria

• Optional tagging/scoping convention is documented.
• Guidance explains when tags are useful and when to omit them.
• Existing memories remain valid without tags.