fix(types): prevent false-positive lexical substitution of ambiguous slang terms

[simongonzalezdc]

Summary

• Fix lexical substitution engine swapping common words ("botón", "agente", "cuero") to slang equivalents when they appeared as regional variants in the cop_informal and money_slang dictionary concepts
• Add ambiguous flag to the Variant interface so dictionary entries can mark variants that have common non-slang meanings and should be excluded from avoid-term generation
• Mark 4 variant entries as ambiguous: botón (es-UY/cop), agente (es-EC/cop), cuero (es-DO/cop), cuero (es-DO/money)
• Add 3 regression tests for the false-positive cases

Root cause

The cop_informal concept lists "botón" as the es-UY slang for "police officer". For es-CO, this became an avoid-term, causing the engine to swap "el botón" (button, UI) → "la tomba" (cop slang). The LLM translation was correct — the corruption happened in post-processing.

Test plan

• All 569 existing tests pass
• 3 new regression tests cover botón, agente, cuero false positives
• Verified real slang (paco, yuta) still gets substituted correctly
• E2E test: "Click the button to grab your report." → "Haga clic en el botón para obtener su informe." (correct)

🤖 Generated with Claude Code

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