PR #13083: portfolio intelligence, streamed history states

This is the branch's own dev server, reading from stage only, with no writes and no uploads. The only stage company with portfolio snapshots is the synthetic Fairhaven Residential test company, which has one week (2026-W39) and two synthetic buildings. The connection was throttled to about 40 KB/s so the streamed page arrives over seconds. Size evidence (81 KB against 288 KB at 70 buildings) comes from the in-test sample in load-report.first-chunk.test.ts, not from this capture.

**1. First paint (server-rendered, 8.6 s under throttle).** The current week is on screen and the note reads "Loading last week's changes and trends…" while the remainder streams.

**2. The route skeleton.** Caveat: this frame came from a client-side re-render after hydration, around 53 s into the throttled dev run, not from the start of the hard load. On a hard load the server streams the page directly.

**3. The history has landed.** The note is gone and no failure banner shows.

Not shown: the "Couldn't load history. Retrying." state. It is covered by PortfolioIntelligenceClient.streamedRest.test.tsx (MUST-FAIL case), which I could not trigger on the dev server without breaking a read.

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