Add base file support for general data to preserve potion type values across scrapes

[Copilot]

The scraper was overwriting potion_types.ts with an empty array on each run because General had no base-loading mechanism — unlike BP/RP containers which seed from src/base/ before scraping.

Changes

• New base JSON files in packages/bedrock-vanilla-data/src/base/general/:

  • potion_types.json — seeds the known values ["Consume", "ThrownLingering", "ThrownSplash"]
  • potion_modifiers.json — empty placeholder following the same pattern

• General.load(folder) — new static method on the General class that reads base values from JSON files before scraping populates the rest

• Output.load() — updated to call General.load(baseFolder/general) alongside the existing edu/vanilla OutputSet loads

• loadStringArray(filepath) — new helper in json.ts for loading plain string arrays; loadEnsure<string> silently wraps string items into { id } objects (by design for BP/RP data), which is incorrect for simple string fields on General

The flow is now consistent with BP/RP containers: base values are loaded first, scraped values are merged on top, and cleanStrings() deduplicates before saving.

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