Fix dependency vulnerabilities

[tanRdev]

Summary

• update vulnerable Bun dependencies and lockfile resolutions
• migrate from the unpatched @mariozechner/pi-coding-agent package to its advisory-listed maintained successor, @earendil-works/pi-coding-agent 0.79.0
• adapt the small SDK API changes needed by that migration
• use the patched Vite 7 line supported by Electron Vite, with a checked-in Electron Vite metadata patch for Babel 8

Verification

• bun audit — 0 vulnerabilities
• lint, contract coverage, import boundaries, and workspace typechecks pass
• all workspace production builds pass

Existing test debt

The full test run reports existing failures that reproduce on untouched main: file-size baseline drift, the system-theme test, a child-process mock, and a tooltip class expectation. Local Electron integration tests also require Electron's binary install step. These are not caused by the dependency diff.

Security review note

The package rename is explicit in dependency names and imports. GitHub's advisories for the original package identify the Earendil Works package/repository and patched 0.78.1+ releases; 0.79.0 also includes the later project-extension fix.