chore: refresh dependencies to latest and move CI to Bun 1.4.2 #1

Current versions:

• @mariozechner/pi-ai: *
• @mariozechner/pi-coding-agent: *
• @biomejs/biome: 2.4.13
• @types/node: ^25.6.0
• @typescript/native-preview: ^7.0.0-dev.20260501.1
• typescript: ^7.0.2
• vitest: ^4.1.5
• node: >=20.0.0

Target versions:

• @earendil-works/pi-ai: 0.87.1 (EXACT)
• @earendil-works/pi-coding-agent: 0.87.1 (EXACT)
• @biomejs/biome: 2.5.14 (EXACT)
• @types/node: 26.6.2 (EXACT)
• @typescript/native-preview: 7.0.0-dev.20260707.2 (EXACT)
• typescript: 7.0.2 (EXACT)
• vitest: 5.0.1 (EXACT)
• node: >=22.19.0

Changes:

• Migrate all @mariozechner/pi-* imports and peerDependencies to @earendil-works/pi-*
• Set peerDependencies ranges to "*" (semantic versioning)
• Add CI workflow for Bun 1.4.2 (push/PR on main + workflow_dispatch)
• Update README install instructions to remove npm registry, keep git:// path
• Add CHANGELOG.md entry
• Patch version bump (0.1.0 → 0.1.1)
• engines.node = >=22.19.0
• No packageManager field
• Lock biome, typescript, vitest, @types/node to exact versions

Acceptance criteria:

• All @mariozechner imports replaced with @earendil-works
• CI passes on Ubuntu + macOS × Node 22,24 with Bun 1.4.2
• npm ci && npm test passes
• typecheck/lint/test all green
• No pre-existing test failures introduced