Add structured tooltip metadata for activities and panel tabs

[Gonza10V]

Motivation

• Provide consistent, editable tooltip content for activities and panels so copy can be managed in one place and updated later.
• Improve the tooltip form/layout (using Mantine Tooltip) to show a clear title, short description, and short instructions to help users understand each activity and panel tab.

Description

• Added tooltip.description and tooltip.instructions metadata to every activity in frontend/src/activities.js so activity text is editable centrally.
• Added tooltip.description and tooltip.instructions metadata to every panel type in frontend/src/panels.js so panel tab text is editable centrally.
• Updated the activity sidebar tooltip rendering in frontend/src/components/activities/Activities.jsx to render a structured, multiline Mantine tooltip with title, description, and instructions and a maw for readability.
• Updated the panel tab tooltip in frontend/src/components/panels/Panel.jsx to render panel-aware content (panel title, description, instructions) and show the current file label; use tooltip fields as the canonical place to change content later.

Testing

• Ran npm run build in frontend/, which completed successfully (build finished) but emitted warnings during bundling (duplicate style key and chunk size warnings).

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Codex Task