feat: Add --test-mode for resilient bootstrap with failure handling

Adds --test-mode flag that marks failed packages as pre-built and
continues bootstrap until all packages are processed. Uses optimal
n+1 retry logic and reports comprehensive failure summary.

Enables discovery of all build failures rather than stopping on first
failure, supporting mixed source/binary dependency workflows.

Fixes #713

Co-developed-with: Cursor IDE with Claude 4.0 Sonnet

Signed-off-by: Lalatendu Mohanty <[email protected]>

Author: LalatenduMohanty