feat: lifecycle inference from the issue timeline (#5)

Fill the board's Steeping / In-review columns (and the calibration actuals)
from real gitea timeline events, replacing the three-column-only v0.

core (@commitea/core):
- inferLifecycle(issue, events, asOf): five-column inference — closed → done;
  open PR ref → review; commit ref → steeping; any triage signal → triage;
  else diagnosis. Earliest event of each kind fixes the stage timestamp.
- Derives actualWorkingDays (work-start → close) — the estimate-vs-actual the
  calibration fit (D3) learns from — and steepingDays (first commit → now) for
  the board age badge.
- workingDaysBetween(): whole Mon–Fri days in [start, end), day-granular.
- normalizeTimeline() + client.getIssueTimeline(): map gitea's raw timeline
  (label/milestone → triage, commit_ref → commit, pull_ref → pull, close,
  reopen), drop the rest. Paginated.

app:
- reconcile now fetches every issue's timeline and returns it keyed by number;
  threaded through the bridge → useBacklog → board/focus.
- issuesToBoardColumns + scheduleFocus run inferLifecycle: real Steeping/In-review
  columns, steeping-age `days` badge, focus-card steeping badge.

Known refinement: gitea's pull_ref fires on any PR mention, so an issue merely
referenced in a PR body can read as In-review; distinguishing closing refs from
mentions needs the PR link's state (later). Re-opening multi-segment actuals
also deferred.

Verified: 63 core tests green (15 lifecycle, incl. workingDaysBetween + the five
transitions), desktop typecheck clean, 14 fixture e2e green, live spec asserts
the board's Done column is populated from real events.

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

packages/core/src/index.ts

@@ -9,7 +9,7 @@ export {
 } from './labels/label-schema.js'
 export type { EstimateLabel, LabelFacts, PriorityLabel } from './labels/label-schema.js'
 
-export { createGiteaClient, normalizeIssue, normalizeMilestone } from './gitea/client.js'
+export { createGiteaClient, normalizeIssue, normalizeMilestone, normalizeTimeline } from './gitea/client.js'
 export type { GiteaClient, ListIssuesOptions } from './gitea/client.js'
 export { GiteaApiError } from './gitea/types.js'
 export type {
@@ -22,8 +22,19 @@ export type {
   GiteaRequestInit,
 } from './gitea/types.js'
 
-export { inferColumnV0, LIFECYCLE_COLUMNS } from './lifecycle/lifecycle-v0.js'
-export type { LifecycleColumn } from './lifecycle/lifecycle-v0.js'
+export {
+  inferColumnV0,
+  inferLifecycle,
+  LIFECYCLE_COLUMNS,
+  workingDaysBetween,
+} from './lifecycle/lifecycle-v0.js'
+export type {
+  LifecycleColumn,
+  LifecycleEvent,
+  LifecycleEventType,
+  LifecycleInference,
+  LifecycleStages,
+} from './lifecycle/lifecycle-v0.js'
 
 export { DEFAULT_ESTIMATE_DAYS, schedule, selectFocus } from './scheduler/scheduler-v0.js'
 export type {