feat(validation): enforce canonical wallet language tags

[bcabreraike-cmyk]

Summary

• add a pinned IANA language-subtag snapshot for offline BCP 47 validation
• reject malformed, non-canonical, ambiguous, and duplicate wallet language tags
• add focused validation fixtures and run them in CI
• document the canonical language format in the schema

Validation

• python -m unittest discover -s tools/tests -p 'test_*.py'
• python -m py_compile tools/validate_csv.py tools/tests/test_validate_csv.py
• full CSV to JSON to JSON Schema validation passed locally; only pre-existing network-chain warnings remain

Dependency

This companion tooling change should be merged before the data update PR targeting main.

Closes #3594

[bcabreraike-cmyk]

CI update: the validation workflow was corrected to use the actual json-tools paths, install tools/requirements.txt, run the tooling fixtures, and compile the package. The new GitHub check now passes. No secrets or reward address were added.

[USS-Supervisor]

Verdict: COMMENT
Risk: LOW
Summary: The json-tools language-tag validator change is focused and internally consistent from the diff I inspected. Required Validate json-tools / Validate tooling is passing, and the focused local unittest and py_compile checks passed in a temporary worktree.
Findings: None from static review. Gate note: I added check-links at 2026-09-03 23:08:58 UTC and polled for the five-minute budget, but no current-cycle Link Check (analysis) run appeared for this PR. I removed check-links before submitting this review, so approval should wait for a fresh successful current-cycle link-check.
Confidence: MEDIUM