docs: resync translated READMEs with English source, add sync check

[Chirag6722]

Closes #62

What this changes

The English README is maintained; the translations follow when someone remembers. This fixes the four places where they had stopped agreeing, and adds a check so the next one is caught in review.

Finding	Where	Evidence it is the translation that is wrong
DM max reach given as 650 mm	README_zh.md	Commit 065c9f2 corrected 650 → 767 mm in README.md on 2026-06-16; Fr, JP and es followed, zh did not
RS Isaac Sim marked planned	README_zh.md, README_JP.md, README_Fr.md	Rows link to Seeed-Projects/reBot-Isaacsim — pushed to this week — while calling the work planned. EN and es already say completed
reSpeaker voice row missing	README_zh.md	12 roadmap rows against 13 everywhere else; #39 added the row to the other languages
RS roadmap table is in French, no section heading	README_JP.md	10 rows of ✅ Terminé / ⏳ Prévu copied from README_Fr.md; the other four files all have ### reBot Arm B601 RS

The Isaac Sim one has a visible cost: #47 is still open asking whether Isaac Sim integration exists. It shipped — but three of five READMEs say otherwise, and two of those contradict themselves within a single table row.

The Japanese RS table is translated from the English table, not from the French one it replaced, so it also picks up the corrections the French copy was missing.

The check

tools/check_readme_sync.py compares each translation against README.md on the things that must not differ:

• number of roadmap tables, and rows per table
• the status glyph (✅ / 🚧 / ⏳) on every row
• the numbers in the specification table

It never compares prose — translators keep their own phrasing, and 1,5 kg is treated as equal to 1.5kg so locale decimal separators do not trip it. .github/workflows/readme-sync.yml runs it on pull requests touching README*.md, along with the checker's own tests. Both actions are SHA-pinned, matching #56 and #58.

Verification

• Run against the pre-fix tree (via a worktree on main), the checker reports exactly the findings above and exits 1:

  README_zh.md: roadmap table 1 has 12 rows, README.md has 13 — a row was added or removed in one and not the other
  README_zh.md: roadmap table 2 row 9 is marked '⏳', README.md marks it '✅'
  README_zh.md: specification reach is [['650'], ['754']], README.md says [['767'], ['754']]
  README_JP.md: roadmap table 2 row 9 is marked '⏳', README.md marks it '✅'
  README_Fr.md: roadmap table 2 row 9 is marked '⏳', README.md marks it '✅'
  

• Run against this branch: 4 translations agree with README.md., exit 0.
• 9 unittest cases pass, covering each real bug as a regression test (stale status, missing row, superseded spec), plus locale decimals, a missing file, and an extra table. One test runs the checker against this repository's actual READMEs.
• actionlint passes on the new workflow. No new links introduced — the Chinese reSpeaker row points at wiki.seeedstudio.com/cn/control_rebot_arm_using_voice_with_respeaker_flex/, confirmed 200, matching the /cn/ convention the other Chinese rows use.

Limits worth knowing

The checker compares structure and numbers, not meaning. It would not have flagged the French-table-in-README_JP.md as "wrong language" — it caught that file only because the French table also carried a stale Isaac Sim status. Detecting a translated file written in the wrong language is a different problem and I have not tried to solve it here.

Note on merge order

This touches README_JP.md:158, which is the line #61 fixes. Whichever merges first, the other needs a trivial rebase — the hunk #61 edits is inside the French table this PR deletes. Merging #61 first is the simpler order.

🤖 Generated with Claude Code

[Chirag6722]

Rebased onto the branch behind #61 so this stands green on its own.

Before the rebase, the link check on this PR reported one error: README_Fr.md:159 pointing at hardware/reBot_B601_RS/readme.md instead of README.md. That is the bug #61 fixes and it lives on main — this PR had already removed the second instance by replacing the French table in README_JP.md, so the count went 2 → 1 rather than anything new being introduced.

Both checks now pass on this branch: Check Documentation Links ✅ and Check README Translations ✅ (444 unique links, 0 errors; 9 unit tests).

Merge order no longer matters. #61 is now an ancestor of this branch, so merging this closes both #60 and #62; merging #61 first also works and leaves this a clean fast-forward. #61 is still worth keeping open as the smaller, more reviewable change if you would rather take the one-line fix first.