[DOCS] ja translation

[bnbong]

Requesting Merging

Description

Part of #59
Refs #60
Closes #63

This PR completes the Japanese documentation localization rollout for FastAPI-fastkit and aligns the related Japanese translation policy/docs with the current localization workflow.

The main goal of this PR is to provide a complete Japanese locale under docs/ja/, improve readability and terminology consistency across translated pages, and clarify that the repository-root CHANGELOG.md remains the canonical English release history.

Type of Change

• BUG FIX
• ADDING NEW TEMPLATE
• FEATURE ADDED/UPDATED
• HOTFIX
• DELETING UNNECESSARY FEATURES
• DOCUMENTATION & DEVOPS
• Etc..

Test Environment

• Local macOS (Apple Silicon / M1), zsh
• Python via uv
• Verified command:
  • uv run mkdocs build
  • Result: Documentation built successfully

Major Changes

• Completed the Japanese docs locale under docs/ja/

  • Added or finalized Japanese pages across:
    • top-level docs pages
    • user-guide pages
    • tutorial pages
    • contributing pages
    • reference pages
  • Japanese locale now has 26 / 26 markdown pages present

• Improved Japanese readability and terminology consistency

  • Reworked translation-style phrasing into more natural Japanese
  • Standardized visible link labels, explanatory text, and glossary-like wording across all phases
  • Kept commands, product names, template ids, file paths, and env vars in English where appropriate

• Updated translation policy and status docs

  • Refined the locale rollout guidance to match the current per-locale / phased workflow
  • Clarified English (docs/en/) as the source of truth
  • Updated Japanese translation-status / translation-guide pages to reflect the current localization policy

• Clarified changelog handling for localized docs

  • Kept the repository-root CHANGELOG.md as the canonical English release history
  • Updated docs/ja/changelog.md to act as a Japanese entry point / wrapper for the canonical English changelog instead of maintaining a separate translated release history
  • Adjusted related wording in Japanese policy/reference pages accordingly

• Refined Japanese docs navigation and cross-page consistency

  • Preserved markdown structure, code fences, tables, admonitions, and internal links
  • Ensured translated pages remain aligned with the English source structure and current MkDocs i18n behavior

Screenshots (optional)

N/A

Etc

• This PR is documentation-focused and does not change runtime product behavior.

[bnbong]

@codex review

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 👍

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[Copilot]

Pull request overview

Completes the Japanese (ja) documentation locale rollout for FastAPI-fastkit by adding the full set of translated pages under docs/ja/, aligning translation policy/status docs with the current localization workflow, and updating translation-status tables to reflect ja reaching 26/26 pages (with the canonical changelog remaining the repo-root English CHANGELOG.md).

Changes:

• Add full Japanese documentation coverage under docs/ja/ (user guide, tutorials, contributing, reference).
• Update translation status pages (English + Korean + Japanese) to mark ja as complete (26/26) and refresh snapshot date.
• Add docs/ja/changelog.md as a wrapper that includes the canonical English CHANGELOG.md.

Reviewed changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
docs/ko/reference/translation-status.md	Updates the KO translation-status table to mark Japanese as complete and refreshes the snapshot note/date.
docs/ja/user-guide/using-templates.md	Adds Japanese translation for the “Using templates” user guide page.
docs/ja/user-guide/quick-start.md	Adds Japanese translation for the quick start guide.
docs/ja/user-guide/installation.md	Adds Japanese translation for installation instructions.
docs/ja/user-guide/creating-projects.md	Adds Japanese translation for project creation guidance.
docs/ja/user-guide/choosing-a-starter.md	Adds Japanese guide to choosing starters/presets vs templates.
docs/ja/user-guide/adding-routes.md	Adds Japanese translation for adding routes to an existing project.
docs/ja/tutorial/getting-started.md	Adds Japanese “getting started” tutorial.
docs/ja/tutorial/domain-starter.md	Adds Japanese tutorial for the domain-starter template/layout.
docs/ja/tutorial/basic-api-server.md	Adds Japanese tutorial for the basic API server template.
docs/ja/tutorial/async-crud-api.md	Adds Japanese tutorial for the async CRUD template.
docs/ja/reference/translation-status.md	Adds Japanese translation-status policy page (source-of-truth + fallback behavior + workflow).
docs/ja/reference/template-quality-assurance.md	Adds Japanese translation for template QA reference.
docs/ja/reference/preset-feature-matrix.md	Adds Japanese translation for preset/feature matrix reference.
docs/ja/reference/faq.md	Adds Japanese FAQ page.
docs/ja/contributing/translation-guide.md	Adds Japanese translation guide for the localization workflow.
docs/ja/contributing/template-creation-guide.md	Adds Japanese guide for creating templates.
docs/ja/contributing/code-guidelines.md	Adds Japanese translation of coding guidelines.
docs/ja/changelog.md	Adds Japanese changelog page that includes the canonical English changelog.
docs/en/reference/translation-status.md	Updates EN translation-status table to mark Japanese as complete and refreshes snapshot note/date.

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