add posthog analytics for llm usage and auth events

Captures per-LLM-call token usage tagged by feature (copilot chat,
track block, meeting note, knowledge sync), plus sign-in / sign-out
and identity. Renderer and main share one PostHog identity so events
from either process resolve to the same user.

See apps/x/ANALYTICS.md for the event catalog, person properties,
use-case taxonomy, and how to add new events.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/x/packages/shared/src/ipc.ts

@@ -25,6 +25,13 @@ const ipcSchemas = {
       electron: z.string(),
     }),
   },
+  'analytics:bootstrap': {
+    req: z.null(),
+    res: z.object({
+      installationId: z.string(),
+      apiUrl: z.string(),
+    }),
+  },
   'workspace:getRoot': {
     req: z.null(),
     res: z.object({

apps/x/packages/shared/src/runs.ts

@@ -21,6 +21,15 @@ export const StartEvent = BaseRunEvent.extend({
     agentName: z.string(),
     model: z.string(),
     provider: z.string(),
+    // useCase/subUseCase tag the run for analytics. Optional on read so legacy
+    // run files written before these fields existed still parse cleanly.
+    useCase: z.enum([
+        "copilot_chat",
+        "track_block",
+        "meeting_note",
+        "knowledge_sync",
+    ]).optional(),
+    subUseCase: z.string().optional(),
 });
 
 export const SpawnSubFlowEvent = BaseRunEvent.extend({
@@ -118,6 +127,13 @@ export const AskHumanResponsePayload = AskHumanResponseEvent.pick({
     response: true,
 });
 
+export const UseCase = z.enum([
+    "copilot_chat",
+    "track_block",
+    "meeting_note",
+    "knowledge_sync",
+]);
+
 export const Run = z.object({
     id: z.string(),
     title: z.string().optional(),
@@ -125,6 +141,8 @@ export const Run = z.object({
     agentId: z.string(),
     model: z.string(),
     provider: z.string(),
+    useCase: UseCase.optional(),
+    subUseCase: z.string().optional(),
     log: z.array(RunEvent),
 });
 
@@ -142,4 +160,6 @@ export const CreateRunOptions = z.object({
     agentId: z.string(),
     model: z.string().optional(),
     provider: z.string().optional(),
+    useCase: UseCase.optional(),
+    subUseCase: z.string().optional(),
 });