Add shader search scopes for assembly keyword filtering

[cobalticarus92]

Motivation

• Shader tab filter should search for keywords not just in list labels but also across captured shader assemblies or the currently selected shader assembly.

Description

• Added a new enum ShaderSearchScopeMode and global g_shaderSearchScopeMode to track the selected search scope.
• Exposed a Search scope combo in the Shader tab UI and adjusted layout widths so the scope selector sits next to the existing Filter and Order controls.
• Implemented a case-insensitive helper ContainsCaseInsensitive and updated the shader list filtering to optionally check rec.cachedDisassembly and rec.editableAssembly when All shader assemblies or Selected shader assembly is chosen.
• Kept existing behavior as the default by treating List labels as the label-only match mode and integrated the new logic alongside the existing label filtering.

Testing

• Ran git diff --check to validate the patch formatting and it completed without errors.
• Ran git status --short to verify the modified file presence in the working tree.
• No compilation or runtime shader tests were executed as part of this change in this PR.

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Codex Task

[chatgpt-codex-connector]

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