fix(dag): make workflow routing deterministic

[LeXwDeX]

Summary

• make the resident Router the sole authority for execution mode, saved-route selection, and full/lite choice
• require file-backed YAML or an exact workflow name returned by list; remove guessable saved-name examples
• expose bounded objectives and graph size in saved-workflow listings
• keep lite reporting gates and downstream skip cascades behaviorally testable

Verification

• core command contracts: 21 passed
• opencode routing, blocks, workflow tool, and parameter schema: 150 passed
• core and opencode tsgo --noEmit: passed
• git diff --check: passed
• independent Spec, Standards, and AHE reviews: P1/P2/P3 = 0