Migrate json configuration files

[cyanzhong]

No description provided.

[Copilot]

Pull request overview

This PR migrates JSON-based configuration files from a top-level array format to a structured object format that includes a $schema reference and an items array, enabling JSON schema validation while remaining backward-compatible.

Changes:

• Added ConfigurationFile<T> wrapper (decodes both legacy array JSON and new { "$schema", "items" } JSON) plus a migration helper.
• Updated Services / KeyBindings / ContentFilters to migrate existing user config files and to decode via ConfigurationFile<T>.
• Updated bundled Services localization JSON files to the new schema-based object format.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
TextGrabber2/Sources/Services.swift	Decode services via ConfigurationFile and attempt on-disk migration when a legacy file already exists.
TextGrabber2/Sources/KeyBindings.swift	Write new default config as schema+items object; migrate and decode using ConfigurationFile.
TextGrabber2/Sources/ContentFilters.swift	Write new default config as schema+items object; migrate and decode using ConfigurationFile.
TextGrabber2/Sources/ConfigurationFile.swift	Introduces schema URL constants, backward-compatible decoding, and a migration routine for legacy array JSON.
TextGrabber2/Resources/Services/en-US.json	Converts bundled services config from array to schema+items object.
TextGrabber2/Resources/Services/zh-Hans.json	Converts bundled services config from array to schema+items object.
TextGrabber2/Resources/Services/zh-Hant.json	Converts bundled services config from array to schema+items object.

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