fix: harden bootstrap cache root resolution

[freshtechbro]

Summary

• make bootstrap cache-root selection lazy so bounded worktrees still win when cwd lookup is unavailable
• move tsup build settings into a shared config and bundle yjs for OpenCode consumer loading
• add regression coverage for the lazy-cwd path and the tsup packaging contract

Verification

• npm run lint
• npm run typecheck
• npm run build
• npm run test
• opencode run --dir /Users/bishopdotun/Documents/DevProjects/opendevbrowser --model opencode/gpt-5-nano --format default --dangerously-skip-permissions "Use the opendevbrowser_prompting_guide tool only. Return the first line of that guide and nothing else."
• node dist/cli/index.js inspiredesign run --brief "Design a premium docs workspace" --url https://linear.app --url https://stripe.com --capture-mode off --include-prototype-guidance --mode json --timeout-ms 120000 --output-dir /tmp/odb-inspiredesign-live-rerun --output-format json

Proof

• OpenCode smoke returned # OpenDevBrowser Best Practices
• Inspiredesign bundle: /tmp/odb-inspiredesign-live-rerun/inspiredesign/a56707ca-4c54-4549-813a-7f87a88d6c49