feat(FilterPanel): add filter panel component with Storybook stories

[krmlp]

📄 Summary

This PR introduces the FilterPanel component for the utility/utility module.

The component is implemented in Pioneer Strict Mode, serving as a reference filter panel that enforces the project's highest architectural standards: explicit configuration, composition-first design, and full i18n/a11y compliance.

• Strict configuration: No default values. All visual and behavioral options (variant, size, position, align, disabled, loading) are required props.
• No embedded strings: All layout values, variants, and spacing are centralized in COMPONENT_CONFIG constant. All user-facing and assistive text (ariaLabel, checkboxListAriaLabel, actionsAriaLabel, selectedFiltersAriaLabel, chipCloseLabel) is passed explicitly for i18n.
• Core components only: Built using Grid, Row, Dropdown, Checkbox, Button, Chip, and Divider.
• Chip-based selection display: Selected filters are displayed as removable chips below the dropdown.
• Composition-first design: Filter items are injected via props array, callbacks handle all state changes externally.
• Svelte 5 runes: Uses $props, $derived, $state, and $effect.

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🧩 Affected Module(s)

• Source Code
• Documentation
• CI / Infra

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✏️ PR Title Format

✅ PR Title: feat(FilterPanel): add filter panel component with Storybook stories

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✅ Checklist

• My branch name follows format: feat/add-filter-panel-component
• My PR title starts with one of the approved types listed above
• My code is formatted using Prettier (pnpm format)
• I ran static analysis (pnpm check) and resolved warnings
• I linked related issues using keywords like Closes #171
• I ensured this PR has no unrelated changes
• This PR is ready for review and does not include unfinished work

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🔗 Related Issues

Closes #171

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