chore: standardize folder names in injected prompts

[maehwasoo]

What

• Standardize folder-name/path examples in injected prompts/docs to a single English canonical set.
• Pin canonical required top-level vault folders (10. Projects, 20. Areas, 30. Resources, 40. Archives, 100. Inbox) in the vault structure doc.

Why

• Keep injected prompt guidance aligned with the actual defaults used by AILSS tools (e.g. capture_note default folder).
• Reduce user confusion without performing any automatic vault folder migrations.

Fixes N/A

How

• Update docs/standards/vault/vault-structure.md to define only the required canonical folder set and remove localized path examples.
• Update docs/ops/codex-skills/prometheus-agent/SKILL.md to keep prompt-safe examples English-only.
• Validation: pnpm build
• Validation: pnpm check