Adds a source-scoped `gbrain dream --source <id>` stage that builds this
worktree's call graph (code-callers/code-callees). Runs lock-free after the
sync lock releases so it never blocks sibling worktrees; a .dream-in-progress
marker dedupes concurrent dreams. --full auto-runs it only when the cycle was
never built; explicit --dream always forces; --no-dream opts out.
The stage parses the cycle's own output and reports the truth, not a flat
"built": a WARN when the schema pack can't extract code symbols, when the
embed phase failed for a missing key, or when 0 edges resolved; OK with the
resolved-edge count otherwise. gbrain exits 0 even when it skips on a held
cycle lock (e.g. autopilot), so that case reports SKIP, not success.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Garry Tan