feat(stats): record android as a reading source

Accept android as a reading-session source from clients and report it as
its own statistics bucket, labelled Android app, beside the iOS app and
Apple Watch. A generated migration adds it to the reading_sessions check
constraint, achievements count Android reading toward Full Orbit and Two
Worlds, and the web charts draw it in a new --pill-android token at hue 95.

packages/types/src/__tests__/reading-session-source-bucket.spec.ts

@@ -16,9 +16,10 @@ describe("toReadingSessionSourceBucket", () => {
     expect(toReadingSessionSourceBucket("manual")).toBe("bookorbit");
   });
 
-  it("keeps iOS and Apple Watch in distinct buckets", () => {
+  it("keeps iOS, Apple Watch and Android in distinct buckets", () => {
     expect(toReadingSessionSourceBucket("ios")).toBe("ios");
     expect(toReadingSessionSourceBucket("watchos")).toBe("watchos");
+    expect(toReadingSessionSourceBucket("android")).toBe("android");
   });
 
   it("maps koreader to koreader", () => {
@@ -36,8 +37,8 @@ describe("toReadingSessionSourceBucket", () => {
 });
 
 describe("reading session source bucket constants", () => {
-  it("exposes all five display buckets", () => {
-    expect(READING_SESSION_SOURCE_BUCKETS).toEqual(["bookorbit", "ios", "watchos", "koreader", "kobo"]);
+  it("exposes all six display buckets", () => {
+    expect(READING_SESSION_SOURCE_BUCKETS).toEqual(["bookorbit", "ios", "watchos", "android", "koreader", "kobo"]);
   });
 
   it("labels every bucket", () => {
@@ -45,12 +46,13 @@ describe("reading session source bucket constants", () => {
       bookorbit: "BookOrbit",
       ios: "iOS app",
       watchos: "Apple Watch",
+      android: "Android app",
       koreader: "KOReader",
       kobo: "Kobo",
     });
   });
 
   it("builds a zero-filled record", () => {
-    expect(emptySourceBucketRecord()).toEqual({ bookorbit: 0, ios: 0, watchos: 0, koreader: 0, kobo: 0 });
+    expect(emptySourceBucketRecord()).toEqual({ bookorbit: 0, ios: 0, watchos: 0, android: 0, koreader: 0, kobo: 0 });
   });
 });

packages/types/src/reading-session-source-bucket.ts

@@ -1,26 +1,28 @@
 import type { ReadingSessionSource } from "./reading-session";
 
-export const READING_SESSION_SOURCE_BUCKETS = ["bookorbit", "ios", "watchos", "koreader", "kobo"] as const;
+export const READING_SESSION_SOURCE_BUCKETS = ["bookorbit", "ios", "watchos", "android", "koreader", "kobo"] as const;
 export type ReadingSessionSourceBucket = (typeof READING_SESSION_SOURCE_BUCKETS)[number];
 
 export const READING_SESSION_SOURCE_BUCKET_LABELS: Record<ReadingSessionSourceBucket, string> = {
   bookorbit: "BookOrbit",
   ios: "iOS app",
   watchos: "Apple Watch",
+  android: "Android app",
   koreader: "KOReader",
   kobo: "Kobo",
 };
 
 // Web/manual and null/unknown history collapse into the general BookOrbit bucket.
-// Native Apple clients remain distinct so device attribution survives aggregation.
+// Native clients remain distinct so device attribution survives aggregation.
 export function toReadingSessionSourceBucket(source: ReadingSessionSource | null | undefined): ReadingSessionSourceBucket {
   if (source === "ios") return "ios";
   if (source === "watchos") return "watchos";
+  if (source === "android") return "android";
   if (source === "koreader") return "koreader";
   if (source === "kobo") return "kobo";
   return "bookorbit";
 }
 
 export function emptySourceBucketRecord(): Record<ReadingSessionSourceBucket, number> {
-  return { bookorbit: 0, ios: 0, watchos: 0, koreader: 0, kobo: 0 };
+  return { bookorbit: 0, ios: 0, watchos: 0, android: 0, koreader: 0, kobo: 0 };
 }

packages/types/src/reading-session.ts

@@ -1,9 +1,9 @@
 import type { ReadingSessionSourceBucket } from "./reading-session-source-bucket";
 
-export const READING_SESSION_SOURCES = ["web", "ios", "watchos", "koreader", "manual", "kobo"] as const;
+export const READING_SESSION_SOURCES = ["web", "ios", "watchos", "android", "koreader", "manual", "kobo"] as const;
 export type ReadingSessionSource = (typeof READING_SESSION_SOURCES)[number];
 
-export const CLIENT_READING_SESSION_SOURCES = ["ios", "watchos"] as const;
+export const CLIENT_READING_SESSION_SOURCES = ["ios", "watchos", "android"] as const;
 export type ClientReadingSessionSource = (typeof CLIENT_READING_SESSION_SOURCES)[number];
 
 export interface BookReadingSession {