Add UI file processing, symbol table tracking, and diagnostics scaffolding for resource_pack/ui/*

[Copilot]

The language server had no awareness of resource_pack/ui/ files — no file type detection, no symbol table entries, and no diagnostic hooks, leaving UI definitions completely unvalidated.

Changes

bedrock-project — FileType & Detection

• Added ui variant to FileType enum
• Added ui/ folder regex match in FileType.detect()
• Added test cases for ui/hud_screen.json detection

bedrock-project — Internal Types

• New internal/resource-pack/ui.ts: UI interface + UI.is() type guard; detects files by presence of a namespace string or object-valued element definitions

bedrock-project — Symbol Table (project/resource-pack/ui/)

• UIElement project type extending BaseObject
• process() function extracts all element identifiers as namespace.element_name IDs, stripping @inheritance suffixes from keys
• ResourcePack gains ui_elements: DataSet<UIElement>, wired into process(), getDataset(), deleteFolder(), deleteFile(), find(), and forEach()
• ResourcePackCollection gains ui_elements: DataSetConnector

bedrock-diagnoser — Diagnostics Hook

• New diagnostics/resource-pack/ui/entry.ts stub: diagnose_ui_document() — ready to add @-inheritance resolution and $-variable tracking
• FileType.ui case wired into the ResourcePack.diagnose_document() switch

Example: how UI elements are indexed into the symbol table

// resource_pack/ui/hud_screen.json
{
  "namespace": "hud",
  "root_panel": { "type": "panel" },
  "health_bar@common.bar": { "size": [81, 9] }
}

Produces entries: hud.root_panel, hud.health_bar in ui_elements.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Build symbol table for @-resolution and $-tracking</issue_title>
<issue_description>## Overview
This issue tracks implementing diagnostics, project provider, and language server support for resource pack UI definitions in Minecraft Bedrock.

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Motivation

• The language server currently does NOT validate, lint, or offer diagnostics for any files in resource_pack/ui/*, even though these power most custom screens and modded menus.
• Users are flying blind for JSON errors, misspelled UI types, broken @ inheritance, missing bindings, or misplaced variables.

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Definition of Done

• UI files are processed by the diagnostics project and symbol table for @-resolution and $-tracking are tracked in the database

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Links

• Reference UI files: Mojang/bedrock-samples/resource_pack/ui
• Schema tracking: [Blockception/Minecraft-bedrock-json-schemas#ui-tracking] (link TBD)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Build symbol table for @-resolution and $-tracking #311

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