Upgrade the Atomic harness to 0.9.27

0.9.27 is the stable release of 0.9.27-alpha.1, with the same
changelog, so the Planner keeps the fixes it already had: workflow-stage
routing and in-flight workflows survive a failed /reload, background
subagent completions reach workflow stages, and slow or cancelled OAuth
token rotation no longer drops a subscription login.
@bastani/atomic-natives and @bastani/pi-ai follow to 0.9.27, and the
natives are published for every platform again, so bun.lock regains the
Windows entries that 0.9.27-alpha.1 lacked. 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: 3666 pass, 3 skips, 0 fail
Assistant-verification: bun run types passed: all workspace checks
Assistant-verification: bun run ci passed: dprint, oxlint (0 errors), tokens, design contract, design record, Impeccable (no new findings)
Assistant-verification: source check passed: @bastani/atomic 0.9.27 dist/builtin lists intercom, mcp, subagents, web-access, workflows; its changelog entries match 0.9.27-alpha.1
Co-authored-by: Alex Lavaee <lavaman131@github.com>