feat: bring project activity matrix into v2.3.2 - #102

Summary

• Adds a project activity matrix to the existing Projects page for both Claude and Codex.
• Provides 30-day and 90-day project-by-day heatmaps plus a stacked daily trend, using the providers' existing indexes without rescanning source logs when the view opens or changes.
• Keeps provider metrics separate and Token-only, with exact tooltips, explicit coverage states, bounded rows and series, keyboard support, narrow-layout scrolling, and refresh-state restoration.
• Enables the matrix by default with an option to hide it, and updates all supported interface languages and documentation.

Verification

• Node tests: 974 passed, 1 existing test skipped, 0 failed.
• Playwright: 153 tests passed, including keyboard, accessibility, theme, and narrow-layout coverage.
• The release-package workflow compiled and verified the VSIX successfully.

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