fix: skip Chinese technical paragraphs already in the target language - #909

Chinese technical paragraphs containing lowercase terms, code identifiers and operator expressions were classified as mixed language and translated back into Chinese. This reproduces with the four paragraphs in #906. The shared detector now accepts short terms only with credible Chinese and local technical context; real foreign sentences, quotations and uncertain text still translate.

The full-page/hover precheck can read protected inline Latin code for language evidence without sending or replacing that code. It preserves hidden/notranslate/candidate boundaries and rejects Chinese inside protected code as evidence for neighboring English or Han-only Japanese. Existing function-word strings are extracted into a byte-identical data module and compressed through the existing userscript data pipeline to keep the build within its inherited size budget. This PR uses #906 only as reproduction material and does not replace its HTTP retry work.

Validation:

• 1,739 targeted language/client/slot/runtime/userscript tests pass; 1,442 scoped coverage tests pass with 100% statements, branches, functions and lines for the five affected core modules.
• Production Chrome MV3 in isolated Edge: all four paragraphs, both plain and code/strong DOM, produce zero Chinese requests/wrappers. Neighboring English, restore/retranslate, dynamic replacement and switching the target to English pass. Tests use a loopback provider fixture.
• Type checking, Chrome/Firefox/userscript builds, userscript verifier, test audit and docs build pass. Userscript is 1,963,619 bytes under the existing 1,964,000-byte budget; no dependencies or budget changed.
• Architecture checks retain one independently reproduced baseline failure: transcription.worker.ts is simultaneously listed as coverage-exempt composition and strict business coverage. Other selected architecture/focus/header checks pass.

Reproduction and saved evidence: docs/reports/chinese-technical-pr-906-20261009/README.md. Online provider quality and Firefox browser interaction were not validated by this scoped fix.