feat(model): parse TOML plans and derive the Plan model

On-time vs. late is judged against the Original Estimate only, never a
re-estimate (ADR-0001); weeks are keyed by their Monday.

src/model/types.ts

@@ -0,0 +1,70 @@
+import type { WeekId } from './week'
+
+export type StatusLevel = 'green' | 'orange' | 'red'
+
+// ── Raw model: as authored, after TOML parse + validation, before derivation ──
+
+export interface RawFeature {
+  name: string
+  start: string // yyyy-mm-dd
+  original: string // yyyy-mm-dd — the Original Estimate
+  reestimates: string[] // yyyy-mm-dd[]
+  delivered?: string // yyyy-mm-dd
+  learning?: string
+  status?: StatusLevel
+  note?: string
+}
+
+export interface RawMilestone {
+  name: string
+  week: string // yyyy-mm-dd
+  requires: string[] // Feature names
+}
+
+export interface RawPlan {
+  title: string
+  features: RawFeature[]
+  milestones: RawMilestone[]
+}
+
+// ── Derived model: render-ready (C2 output) ──
+
+export type MarkerKind =
+  | 'original' // ◯ Original Estimate, not yet delivered
+  | 'reestimate' // △ a slip to a later week
+  | 'delivered-on-time' // ◉ delivered on/before the Original Estimate
+  | 'delivered-late' // ▲ delivered after the Original Estimate
+
+export interface Marker {
+  week: WeekId
+  kind: MarkerKind
+}
+
+export interface FeatureRow {
+  name: string
+  startWeek: WeekId
+  barEndWeek: WeekId
+  markers: Marker[]
+  delivered: boolean
+  onTime: boolean | null // null while in-flight
+  status?: StatusLevel
+  note?: string
+  learning?: string
+  slipCount: number // number of Re-estimates
+}
+
+export interface MilestoneLine {
+  name: string
+  week: WeekId
+  requires: string[]
+  unmet: string[] // required Features not delivered on/before this week
+}
+
+export interface Plan {
+  title: string
+  weeks: WeekId[]
+  rows: FeatureRow[]
+  milestones: MilestoneLine[]
+  nowWeek: WeekId
+  nowInRange: boolean
+}