Two paired engine semantics fixes:
1. trigger_event_id is now the authoritative semantic anchor. When a
rule carries trigger_event_id, the engine no longer falls back to
the proceeding's trigger date — it resolves the anchor via
CalcOptions.TriggerEventAnchors keyed by paliad.trigger_events.code.
Missing anchor renders the rule as IsConditional (empty date) and
propagates via courtSet so descendants also surface as conditional.
Fixes the RoP.109.5 bug where the engine fabricated a date 2 weeks
before the user's SoC instead of waiting for the oral_hearing date.
2. priority='optional' rules are suppressed from the default
Calculate output. Callers (paliad /tools/procedures,
youpc.org/deadlines) opt in via CalcOptions.IncludeOptional=true to
restore the legacy "show optional applications" behaviour. The
suppression cascades through skippedIDs so child rules drop too.
Wire shape additions:
- CalcOptions.IncludeOptional bool
- CalcOptions.TriggerEventAnchors map[string]string
- Timeline.RulesAwaitingAnchor int (count of suppressed-by-missing-
anchor rules, for caller telemetry / "N rules need an anchor" UX)
Existing before-court-set-anchor tests opt in to IncludeOptional=true
to preserve their non-optional-related test intent.
Refs: youpcorg/head delegations #2568 + #2570, m/paliad#153 (Litigation
Builder PRD path).
