Refactor CLI commands to delegate to reusable operations

[JeBobs]

• refactor resource import/export commands to delegate work to reusable operations for loading and saving resources
• add a dedicated texture porting operation and simplify the PortTexture CLI command to invoke it
• introduce string table operations for loading, merging, and persisting ResourceDB data and update the command to use them

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Handle file outpaths when porting textures

The new SetArgs fixes --outpath so callers can pass a file path, but PortTextureOperation still only sets outPath when the destination is the source file or an existing directory. If the user supplies a valid file path (per the CLI contract allowing file/folder paths), the branch at lines 159‑163 leaves outPath empty and the subsequent bitmap copy and file writes throw because they try to write to an empty path. This regression makes porting fail whenever --outpath targets a specific file instead of a directory.

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