docs(skills): recommend splitting inline locale blocks by section

[otnc]

Summary

• Fix bug(s)
• New feature(s)
• Others

The kiritan Agent Skill's inline-strategy section now explicitly recommends splitting at every natural section boundary into its own locale=en/locale=ja block pair, instead of wrapping a whole document's content in one pair per locale. Adds a side-by-side example (recommended split form vs. the monolithic form) and the reasoning: both build to the same output, but the split form keeps each locale pair next to its counterpart, keeps diffs scoped to the section that changed, and avoids scrolling through a wall of one language before the other begins. Also cross-referenced from "Common mistakes to avoid".

This repo's own base/*.base.md files already follow the split style throughout (checked — base/DESIGN.base.md alone has 73 block pairs), so no rewrite of existing sources was needed.

Docs only (an Agent Skill file, not npm-published).

Why?

Requested: the Skill should steer agents toward the more readable, section-split style by default.

Related issue(s)

closes

Check

• Check if duplicate PR(s) already exist.
• Read CONTRIBUTING.md (rules)
• Run npm run check (lint & format)
• Run npm run typecheck
• Run npm run test (functions test)
• Run npm run build (dist/)
• (optional) Run npm run test:coverage and check nothing new went uncovered