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/gitea/client.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 
-import { createGiteaClient, normalizeIssue } from './client.js'
+import { createGiteaClient, normalizeIssue, normalizeTimeline } from './client.js'
 import { GiteaApiError, type FetchLike, type GiteaConfig, type GiteaRequestInit } from './types.js'
 
 const CONFIG: GiteaConfig = {
@@ -44,6 +44,31 @@ function stubFetch(body: unknown, status = 200): {
   return { fetch, calls }
 }
 
+describe('normalizeTimeline', () => {
+  it('maps known gitea event types to lifecycle signals and drops the rest', () => {
+    const events = normalizeTimeline([
+      { type: 'label', created_at: '2026-01-06T09:00:00Z' },
+      { type: 'milestone', created_at: '2026-01-06T09:05:00Z' },
+      { type: 'commit_ref', created_at: '2026-01-07T12:00:00Z' },
+      { type: 'pull_ref', created_at: '2026-01-08T12:00:00Z' },
+      { type: 'comment', created_at: '2026-01-08T13:00:00Z' }, // dropped
+      { type: 'add_dependency', created_at: '2026-01-08T14:00:00Z' }, // dropped
+      { type: 'close', created_at: '2026-01-12T09:00:00Z' },
+    ])
+    expect(events).toEqual([
+      { type: 'triage', at: '2026-01-06T09:00:00Z' },
+      { type: 'triage', at: '2026-01-06T09:05:00Z' },
+      { type: 'commit', at: '2026-01-07T12:00:00Z' },
+      { type: 'pull', at: '2026-01-08T12:00:00Z' },
+      { type: 'close', at: '2026-01-12T09:00:00Z' },
+    ])
+  })
+
+  it('skips events missing a timestamp', () => {
+    expect(normalizeTimeline([{ type: 'commit_ref', created_at: '' }])).toEqual([])
+  })
+})
+
 describe('createGiteaClient.getIssue', () => {
   it('returns a normalized, typed issue from canned JSON', async () => {
     const { fetch } = stubFetch(RAW_ISSUE)