refactor(errors): defer mutation errors to global handler

Now that MutationCache toasts via toUserMessage by default, the per-hook
onError duplicates drop away. Also normalizes inline query-error UI and
surfaces a previously-silent failure.

Mutations — removed redundant onError toasts:
- network-selector: useAcceptInvitation, createNetwork (inline)
- network-settings: useInviteMembers, useRevokeInvitation, useRemoveMember
- network-billing: useCreateCheckoutSession, useCreatePortalSession
  (onSuccess toasts stay — they carry domain context like network name)

Queries — consistent inline error UX via toUserMessage:
- network-selector: failed-to-load state gets a "Try again" button
- network-billing: "Couldn't load billing" includes friendly reason
- network-settings: useNetworkInvitations failure now surfaces a hint
  (previously rendered as "0 pending" — silently wrong)

Trimmed noisy JSDoc from PR 1 files (errors.ts, query-client.ts,
app-error-boundary.tsx, error-fallback.tsx, ipc-utils.ts).

js/src/lib/errors.ts

@@ -1,9 +1,6 @@
 import { z } from "zod";
 import { appEnv } from "@/config/env";
 
-/**
- * Thrown by the API client for any non-2xx response.
- */
 export class ApiError extends Error {
   constructor(
     public status: number,
@@ -16,9 +13,8 @@ export class ApiError extends Error {
 
 /**
  * Thrown when a free-plan network attempts to create a non-container particle
- * after hitting its daily message limit. Callers should surface an upgrade
- * prompt; compose UI should also disable triggers proactively via
- * `useNetworkUsage` rather than relying on this throw.
+ * after hitting its daily message limit. Compose UI also disables triggers
+ * proactively via `useNetworkUsage` — this throw is a last-line defense.
  */
 export class QuotaExceededError extends Error {
   constructor(public readonly networkId: string) {
@@ -33,11 +29,6 @@ function normalizeMessage(message: string): string {
   return message.replace(IPC_PREFIX, "").replace(/^Error:\s*/, "").trim();
 }
 
-/**
- * Maps any thrown value to a short, user-facing string. Used by the global
- * MutationCache toast handler, the error-boundary fallback, and any call site
- * that wants to surface an error in the UI.
- */
 export function toUserMessage(err: unknown): string {
   if (err instanceof ApiError) {
     if (err.status === 401) return "Please sign in again.";
@@ -69,11 +60,7 @@ export function toUserMessage(err: unknown): string {
 
 type ErrorContext = Record<string, unknown>;
 
-/**
- * For expected-but-worth-recording failures (silent-catch sites). In dev,
- * prints to console. In prod today this is a no-op; PR 4 wires this up to
- * Sentry breadcrumbs without touching call sites.
- */
+/** Expected-but-recordable failures. Dev logs; prod is currently a no-op. */
 export function logError(err: unknown, context?: ErrorContext): void {
   if (appEnv === "dev") {
     // eslint-disable-next-line no-console
@@ -81,11 +68,7 @@ export function logError(err: unknown, context?: ErrorContext): void {
   }
 }
 
-/**
- * For unexpected failures the user may not have seen (render crashes, query
- * errors, background mutations). Always surfaces somewhere. PR 4 wires this
- * up to `Sentry.captureException`.
- */
+/** Unexpected failures the user may not see. Always surfaces somewhere. */
 export function reportError(err: unknown, context?: ErrorContext): void {
   // eslint-disable-next-line no-console
   console.error("[error]", err, context ?? {});