docs: update translated READMEs to reference Poetry instead of requirements.txt

[mvanhorn]

Summary

The 9 translated READMEs still show requirements.txt in their project-structure tree. The repo migrated to Poetry in #380 and PR #433 updated only the English README to match (pyproject.toml + poetry.lock). This patch brings the translated structure trees in line.

Why this matters

#502 flagged that the api/ directory has no requirements.txt. The English README is correct; the 9 translated READMEs still list it, which sends readers looking for a file that does not exist.

Changes

For each translated README, the single line:

│   └── requirements.txt  # <translated phrase>

is replaced with the two-line layout that already exists in the English README:

│   ├── pyproject.toml     # <translated phrase> (Poetry)
│   └── poetry.lock        # <translated phrase, locked dep versions>

Per-language comments translate "Python dependencies (Poetry)" and "Locked Python dependency versions" into the same register the file already uses. README.vi.md keeps English text for this entry, matching the prior line's existing style.

Testing

Docs-only change. No test runner invoked. Spot-checked the tree alignment in each file.

Notes

Touches the same 9 translated READMEs as the open #508 (docker-compose v1 → v2), but on different lines (project-structure tree vs docker-compose command). Can merge in either order; will rebase if #508 lands first.

Closes #502

AI was used for assistance.

[gemini-code-assist]

Code Review

This pull request updates the directory structure documentation across multiple localized README files to reflect the switch from requirements.txt to Poetry-based dependency management using pyproject.toml and poetry.lock. Feedback was provided regarding the Chinese README to maintain consistent spacing between English and Chinese characters in the file's comments.

[gemini-code-assist]

The spacing between English and Chinese characters is inconsistent with line 161 and the rest of the file (e.g., line 158). To maintain consistency with the existing style, the spaces around "Python" should be removed.

Suggested change

	│ └── poetry.lock # 已锁定的 Python 依赖版本
	│ └── poetry.lock # 已锁定的Python依赖版本