feat: read the real gitea backlog into the app (P1 thin slice)

The app now displays its own live backlog instead of fixtures. First
end of the sync loop — the tap-root (#1) grows list reads and a read
path through the Electron main process.

- @commitea/core: client gains `listIssues` (paginated, PRs excluded)
  and `listMilestones`; a `lifecycle-v0` mapper (closed→done,
  labelled/milestoned→triage, bare→diagnosis — steeping/review await
  event inference in P1-5). +10 unit tests.
- main: gitea bridge over IPC (token stays in main, never the renderer);
  config from env / .env.local; gated off under COMMITEA_E2E so the
  committed e2e stays on fixtures. Preload exposes the typed bridge.
- renderer: useBacklog() reconciles once on mount; issuesToBoardColumns
  shapes real issues into The pot. Board takes optional real columns +
  a loading state, falling back to demo fixtures when unconfigured.

Verified: 14 e2e green (fixture mode) + a gated live spec that launches
against the real repo — the board renders the actual 25 open + 9 closed
issues (screenshot). SQLite mirror + reconcile-on-a-timer + lifecycle
event inference are the next slices (#2/#3/#5).

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

packages/core/src/gitea/client.test.ts

@@ -107,6 +107,50 @@ describe('createGiteaClient.getIssue', () => {
   })
 })
 
+describe('createGiteaClient.listIssues', () => {
+  /** Stub fetch that pages 50-at-a-time and records the paths it was asked for. */
+  function pagedFetch(pages: unknown[][]): { fetch: FetchLike; paths: string[] } {
+    const paths: string[] = []
+    const fetch: FetchLike = (url) => {
+      paths.push(url)
+      const page = Number(/[?&]page=(\d+)/.exec(url)?.[1] ?? '1')
+      const body = pages[page - 1] ?? []
+      return Promise.resolve({
+        ok: true,
+        status: 200,
+        json: () => Promise.resolve(body),
+        text: () => Promise.resolve(''),
+      })
+    }
+    return { fetch, paths }
+  }
+
+  it('walks every page until a short page ends it', async () => {
+    const full = Array.from({ length: 50 }, (_, i) => ({ ...RAW_ISSUE, number: i + 1 }))
+    const tail = [{ ...RAW_ISSUE, number: 51 }]
+    const { fetch, paths } = pagedFetch([full, tail])
+
+    const issues = await createGiteaClient(CONFIG, fetch).listIssues()
+    expect(issues).toHaveLength(51)
+    expect(paths).toHaveLength(2) // stopped after the short second page
+    expect(paths[0]).toContain('/issues?type=issues&state=all&page=1&limit=50')
+  })
+
+  it('excludes pull requests even if the API returns them', async () => {
+    const { fetch } = pagedFetch([
+      [{ ...RAW_ISSUE, number: 1 }, { ...RAW_ISSUE, number: 2, pull_request: { url: 'x' } }],
+    ])
+    const issues = await createGiteaClient(CONFIG, fetch).listIssues()
+    expect(issues.map((i) => i.number)).toEqual([1])
+  })
+
+  it('passes the state filter through', async () => {
+    const { fetch, paths } = pagedFetch([[]])
+    await createGiteaClient(CONFIG, fetch).listIssues({ state: 'open' })
+    expect(paths[0]).toContain('state=open')
+  })
+})
+
 describe('normalizeIssue', () => {
   it('defaults missing labels/assignees/body to empty and maps a closed state', () => {
     const issue = normalizeIssue({