Upgrade the Atomic harness to 0.9.27-alpha.1

0.9.27-alpha.1 has no breaking changes from 0.9.26. For the Planner it
keeps workflow-stage routing and in-flight workflows reachable across a
failed /reload, delivers background subagent completions to workflow
stages, and stops slow or cancelled OAuth token rotation from dropping a
subscription login. @bastani/atomic-natives and @bastani/pi-ai follow to
0.9.27-alpha.1; Atomic's @earendil-works packages stay at 1.0.2. The five
builtin packages are unchanged, so BUILTINS_OFF still turns off each one
for the isolated Planner.

Assistant-workflow: inline
Assistant-model: Claude Opus 5.5
Assistant-verification: bun test passed: 3665 pass, 3 skips, 0 fail
Assistant-verification: bun run types passed: all 9 workspace checks
Assistant-verification: bun run ci passed: dprint, oxlint, tokens, design contract, design record, Impeccable (no new findings)
Assistant-verification: source check passed: @bastani/atomic 0.9.27-alpha.1 dist/builtin lists intercom, mcp, subagents, web-access, workflows; changelog has no breaking changes since 0.9.26
Co-authored-by: Alex Lavaee <lavaman131@github.com>