docs: add bilingual localized strings CSV workflow

[nowaytofindavailableone]

Summary

• Add a practical Russian and English guide for exporting, reviewing, and importing REDkit localized strings as CSV.
• Document Project ID-space setup, collision-safe ID ranges, editor export/import, collaboration handoff, verification, and conservative CSV/schema/conflict limitations.
• Add mirrored navigation entries.

Changed files

• docs/unofficial_docs/guides/localized_strings_csv.md
• docs/en/unofficial_docs/guides/localized_strings_csv.md
• mkdocs.yml
• mkdocs.en.yml

Both pages include the required AI-assisted-content warning and a Sources section. The pages do not claim that the workflow was runtime-tested in REDkit; version-specific behavior and schema details are explicitly caveated.

Sources

• HOW-TO: Use ID spaces for localization modding — Project ID spaces, bounds, lifetime/reservation, and collision-safe ranges.
• TOOL: Localized Strings Editor — CSV export/import, collaboration, editor workflow, and filename/location.
• Localized Strings Editor — community terminology and editor navigation.

Review and validation

• Pass A: independent fact/safety and translation reviewers, both PASS; an earlier reviewer-safe bundle attempt was superseded after prohibited metadata exposure, and the final immutable retry passed.
• Pass B: independent fact/safety reviewer 2c9e36cd-300e-4ff2-8c0d-ef5dadcaa871 and translation reviewer c5f20266-1c33-4c79-821a-4694bdd1b89b, both PASS before the deadline; reviewer IDs did not overlap Pass A.
• Isolated non-strict RU and EN MkDocs builds passed.
• Required strict RU/EN builds were attempted. Both fail on the same pre-existing nested-nav configuration warning in the untouched base snapshot; the changed snapshot has no additional strict failure. Base-only and changed non-strict builds were compared, and outputs were kept outside the repository.
• git diff --check and staged checks passed; the commit contains exactly the four intended paths.

Runtime REDkit/game testing: not run; REDkit and a test game were not available in this documentation/build environment.