feat(admin): insights is the one analytics surface (issue #181)

[edgehero]

First PR of #181: insights becomes the ONE analytics surface. The COSTS view (c), the GRAPH view (g), /dispatch costs (incl. whatif) and /dispatch graph (incl. html) are removed; bare /dispatch insights [7d|30d|mtd] [--no-open] [--full-paths] writes AND opens the artifact (no html verb — the removed verb answers usage on purpose, because a dead verb that half-works is drift), insights whatif <provider/model> --flow <flow> carries the estimator forward, and the overlay's new i key runs the same write-and-open between overlays.

What survives, deliberately

dispatch_costs (the machine path — it returns the cost fold only; topology stays non-model-callable, so the tool count pin stands at 15), every pure layer (foldCosts, buildGraphModel, buildGraphScene, buildGraphHtml with its full suite as the scene's pinned reference, insights-html), the assemblers, renderWhatIf and renderBudget. No plain-text analytics form: the artifact writes and prints its file:// URL even headless, which IS the degraded path.

The commits

1. Command grammar: USAGE/KNOWN_SUBCOMMANDS/description drop the two subcommands together (the member-for-member pin holds); insightsHtmlCommand becomes insightsCommand (tokens shift one left); costsWhatIf moves verbatim to insightsWhatIf; completion offers the windows, whatif, and the priced catalog as the long-tail model picker. Wiring's two channel tests retarget (the whatif reply; bare insights end-to-end through real deps into a temp PI_GRAPH_DIR, with the SSH skip said after the URL); junk-argument pins cover the dead verb and the removed subcommands; graph-command.test.mjs is deleted with its isHeadlessEnv block moved beside its only caller.
2. Dashboard excision: the overlay returns to four views. The contiguous COSTS+GRAPH render region, their state, seams, keys and refresh policies leave; the shared helpers every surviving view uses stay; dashboard.ts drops its pricing/costs/graph-model imports entirely. The i key resolves the overlay with { action: "openInsights" } and handleDashboardAction writes-and-opens between overlays (the addTrigger route — no dep seam, no TUI suspend bracket, and BEFORE the dialog guard so an older pi without dialogs still reaches the one analytics surface). The footer becomes ↑↓ open · a add · w pauses · l logs · i insights · p/r pause · q quit (69 of 76 columns, arithmetic comment re-run). ~950 lines of view tests are deleted whole — their fold/renderer pins live on in costs.test.mjs and the artifact suites — and one replacement test pins the new footer, the inert c/g, and the i done-action. Zero surviving tests needed edits.
3. render.mjs: renderCosts and renderGraph lose their last callers and leave with their exclusive helpers; renderWhatIf (the insights whatif reply) and everything else stay.
4. Specs, plus the one code change the spec pass exposed: removing the terminal surfaces left REQ-TOPOLOGY-GRAPH (h)'s next/overdue facts with NO surface — the TUI and text renderers carried them alone — so the scene's trigger tips now render next 191d / overdue 2h against the page's own generation instant, landed in the same PR that removed their last other home, with pins. REQ-INSIGHTS-HTML-EXPORT absorbs REQ-GRAPH-HTML-EXPORT's normative clauses verbatim (that entry is SUPERSEDED; the ID stays a permanent address). REQ-COST-ANALYTICS and REQ-TOPOLOGY-GRAPH restate their surfaces with the labeling/honesty rules untouched. REQ-ADMIN-VIA-PI-EXTENSION's command list updates; its tool list UNCHANGED, checked. DES-ADMIN-VIA-PI-EXTENSION drops to four views and records the i-key route's rationale. OQ-024 rescoped. INT-* UNCHANGED, checked (grep-verified).

Docs and READMEs still describe the old surfaces on purpose: the docs/images pass lands last in this series, after the page gains its budget panel and line charts, so the screenshots are shot once.

Suite green in the CI posture at every commit (final: 2181 tests, 0 skipped, live Valkey). Net: −2,540 lines.