feat(web): anomalies live in the alerts hub - #2320

🟡 Confidence 6/10 · needs attention. Two untested correctness gaps on the new anomaly editor paths; the incident, anomalies-detail and lab files went unread as the pass ran out of time.
_{2 warnings −2 · 1 note · tests partial −1 · risk medium · 0/1 new units observable −1}

Moves anomalies into the Alerts hub: an Anomaly rule mode, an anomaly evidence incident page, and /anomalies redirecting to the hub. Two correctness gaps remain in the new anomaly branches. The McpQueryError issues in page/registry.ts are unrelated MCP tool failures the diff does not touch. Unread: incident page, anomalies-detail, kit and lab files.

• The Inbox gains an Anomalies view driven by signal and anomalyStatus
• Rule editor gains an Anomaly mode with scope and per-tier routing
• Anomaly incidents draw the detector's evidence instead of the rule chart
• /anomalies redirects to /alerts?signal=anomaly; the list page is removed

Findings

Treat a chain as routing here too: add `form.escalationChainId === null` and `(form.escalation?.escalationChainId ?? null) === null` to the destination condition, mirroring `isNotifyMissingOf`.

	if (current === "anomaly") {
		const left = leaveAnomaly(form)
		if (next === "builtin") return { form: left, notice: null }
		const moved = moveToKind(left, next)
		return { form: carryThreshold(left, moved.form), notice: moved.notice }
	}

Still open from earlier reviews

• 🔵 Note · F5 · The Signals row's label points at a div, not at the toggle group · apps/web/src/page/alerts/editor/view-query.ts:381

Fixed since the last review

• ✅ F10 · A just-resolved anomaly reads "now ago" in the resolved list
• ✅ F11 · Test named for carrying both tiers' destinations asserts neither

Production impact

_{5301042 · Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}