feat: capacity-aware scheduling (#8) — real focus factors drive every forecast

Turns the single-serial-worker scheduler into a capacity-aware, multi-lane one.
Configured team members become lanes; an issue runs on its assignee's lane (or the
earliest-free lane), its duration scaled by that lane's throughput
(focusFactor × allocation). Every forecast — Focus cone, Runway, milestone
drill-in — is now capacity-aware.

core (@commitea/core):
- capacity/capacity-v0: CapacityMember + capacityPerWorkday + parseCapacityConfig
  (clamps, drops invalid; degrades to []).
- scheduler/scheduler-capacity-v0: scheduleWithCapacity reuses the v0 topo order +
  critical path, re-lays work across lanes (layoutOnLanes, resolveLanes, makespan).
  Empty workers → the single serial plan verbatim.
- forecast() gains options.workers: each MC trial lays sampled durations across the
  lanes and takes the makespan; serial path unchanged. SchedulableIssue gains
  assignee; ScheduledItem gains worker.
- 11 new tests (parse/clamp, parallelism halves makespan, speed scaling, assignee
  routing, cross-lane deps, forecast makespan shrinks with lanes).

app:
- pm-state capacity/members.json read (readCapacity + pmstate:capacity bridge);
  useCapacity hook → workers; forecastBacklog/runwayView/milestoneView pass workers.
- Runway Capacity card shows the real config (person · focus · alloc · pd/day).

Config lives in pm-state (D4); seeded christian(0.8)/stephen(0.6×0.5). Degrades to
the fixture/serial when absent.

Verified: 128 core tests green, desktop typecheck clean, 14 fixture e2e green. Live:
the capacity card is real, and the P2 forecast shifts 32d→37d — honest, since real
focus factors (<1) replace the v0 focus-1.0 assumption.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/src/capacity/capacity-v0.ts

@@ -0,0 +1,49 @@
+/**
+ * Capacity model (#8). A member's throughput is `focusFactor × allocation` =
+ * ideal person-days of project work delivered per calendar working day. The
+ * scheduler treats each member as a lane whose task durations are scaled by that
+ * rate (a 0.5-capacity person takes twice as long on an est/2d task). Config
+ * lives in the pm-state repo (`capacity/members.yaml/json`, D4); estimates are
+ * in ideal person-days (pm-state.md).
+ */
+
+export interface CapacityMember {
+  /** gitea login. */
+  person: string
+  /** Productive fraction of a working day (0..1). */
+  focusFactor: number
+  /** Fraction of that allocated to this project (0..1). */
+  allocation: number
+}
+
+/** Ideal person-days delivered per calendar working day. */
+export function capacityPerWorkday(m: CapacityMember): number {
+  return m.focusFactor * m.allocation
+}
+
+function clamp01(n: unknown, fallback: number): number {
+  return typeof n === 'number' && Number.isFinite(n) ? Math.min(1, Math.max(0, n)) : fallback
+}
+
+/**
+ * Validate a raw capacity config (`{ members: [...] }`) into members. Unknown
+ * shapes degrade to `[]` (→ the scheduler falls back to a single worker), never
+ * throw. focusFactor/allocation clamp to [0,1]; a member without a person is dropped.
+ */
+export function parseCapacityConfig(raw: unknown): CapacityMember[] {
+  const list = (raw as { members?: unknown })?.members
+  if (!Array.isArray(list)) return []
+  const out: CapacityMember[] = []
+  for (const m of list) {
+    const r = (m ?? {}) as Record<string, unknown>
+    const person = typeof r.person === 'string' ? r.person.trim() : ''
+    if (!person) continue
+    const member: CapacityMember = {
+      person,
+      focusFactor: clamp01(r.focusFactor, 0.8),
+      allocation: clamp01(r.allocation, 1),
+    }
+    if (capacityPerWorkday(member) > 0) out.push(member)
+  }
+  return out
+}