feat(substations): add as 9th entry point (homepage + footer + counts) (#223)

Substations data, API, tile layer, and detail pages shipped across
PRs #185-#201 but the homepage/footer entry points were never added
(PR #202 was closed without replacement). From the user perspective,
substations simply weren't discoverable — no card on the landing page,
no footer link, no count in the stats rail.

This adds the missing surface-level entry points:
- New 9th entity card (Infrastructure · OSM · ≥69 kV · ~60k rows)
- Footer link in 'The data' column
- API endpoint listed in 'For developers'
- Live count wiring via useEntityCounts
- Section heading: 'Eight entry points' → 'Nine entry points'

Unblocks Victor's DM about 'not seeing Substations anywhere'.

Co-authored-by: texture-coding-agent <coding-agent@texturehq.com>

Author: texture-fleet-agent[bot]

app/(shell)/page.tsx

@@ -79,6 +79,15 @@ const ENTITY_CARDS = [
     countKey: "pricingNodes" as const,
     tags: ["LMP", "DA / RT"],
   },
+  {
+    num: "09",
+    cat: "Infrastructure",
+    href: "/substations",
+    name: "Substations",
+    desc: "Step-up, step-down, and switching substations \u2014 voltage class, owner, and interconnected assets normalized from OpenStreetMap.",
+    countKey: "substations" as const,
+    tags: ["OSM", "\u226569 kV"],
+  },
 ];
 
 const LEDGER_ROWS = [
@@ -164,6 +173,7 @@ const ENDPOINT_DEFS = [
   { path: "/transmission-lines", countKey: "transmissionLines" as const, suffix: "lines" },
   { path: "/ev-stations", countKey: "evStations" as const, suffix: "stations" },
   { path: "/pricing-nodes", countKey: "pricingNodes" as const, suffix: "nodes" },
+  { path: "/substations", countKey: "substations" as const, suffix: "substations" },
   { path: "/programs", countKey: "programs" as const, suffix: "programs" },
   { path: "/search", desc: "full-text" },
   { path: "/changelog", desc: "every edit, attributed" },
@@ -200,6 +210,7 @@ export default function LandingPage() {
     transmissionLines: formatCount(counts.transmissionLines),
     evStations: formatCount(counts.evStations),
     pricingNodes: formatCount(counts.pricingNodes),
+    substations: formatCount(counts.substations),
   };
 
   return (
@@ -928,7 +939,7 @@ export default function LandingPage() {
           <div className="section-head">
             <div>
               <div className="kicker">01 &middot; Browse</div>
-              <h2 className="section-title">Eight entry points, one connected graph.</h2>
+              <h2 className="section-title">Nine entry points, one connected graph.</h2>
             </div>
             <p className="section-desc">
               Every utility links to its territory, every territory to its operator, every plant to its interconnection.
@@ -1331,6 +1342,7 @@ export default function LandingPage() {
               <Link href="/explore">Territories</Link>
               <Link href="/grid-operators">Operators</Link>
               <Link href="/power-plants">Power plants</Link>
+              <Link href="/substations">Substations</Link>
               <Link href="/ev-charging">EV charging</Link>
               <Link href="/changelog">Full changelog</Link>
             </div>

hooks/useEntityCounts.ts

@@ -13,6 +13,7 @@ export interface EntityCounts {
   pricingNodes: number | null;
   programs: number | null;
   territories: number | null;
+  substations: number | null;
 }
 
 export const COUNT_ENDPOINTS: { key: keyof EntityCounts; path: string }[] = [
@@ -26,6 +27,7 @@ export const COUNT_ENDPOINTS: { key: keyof EntityCounts; path: string }[] = [
   { key: "pricingNodes", path: "/api/v1/pricing-nodes?limit=1" },
   { key: "programs", path: "/api/v1/programs?limit=1" },
   { key: "territories", path: "/api/v1/territories?limit=1" },
+  { key: "substations", path: "/api/v1/substations?limit=1" },
 ];
 
 export function useEntityCounts(): EntityCounts {
@@ -40,6 +42,7 @@ export function useEntityCounts(): EntityCounts {
     pricingNodes: null,
     programs: null,
     territories: null,
+    substations: null,
   });
 
   useEffect(() => {