Upgrade the Atomic harness to 0.9.26

0.9.26 is the stable release of the 0.9.26 prereleases already in use: a
workflow stage's ask_user_question reaches Decisions, managed workflow
PostgreSQL comes back after a shutdown, and a new session can resume a
run whose owning session crashed, now with database ownership fencing.
Its one breaking change, McpOAuthCredentialStore taking a server name, is
not used here. @bastani/atomic-natives and @bastani/pi-ai follow to
0.9.26; 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: 1936 pass, 2 PostgreSQL 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 0.9.26 dist/builtin lists intercom, mcp, subagents, web-access, workflows; no McpOAuthCredentialStore use
Co-authored-by: Alex Lavaee <lavaman131@github.com>