feat: deliver realtime errors to subscription streams (v26.1.0)

[ArnabChatterjee20k]

Ports the realtime error-handling fix from sdk-generator#1857 to the Flutter SDK.

What's Changed

• Fixed: realtime policy-violation errors are now delivered to active subscription streams instead of thrown from the message handler

Previously handleError threw an AppwriteException from inside the websocket message handler, where consumers could not catch it. It now calls subscription.controller.addError(...) on every active subscription, so errors surface through the subscription stream's onError.

Bumps SDK to 26.1.0.

Scope is realtime-only — no other API surface changed. The e2e coverage for this fix lives in the sdk-generator repo (already merged in #1857); this repo carries no realtime e2e tests.

[greptile-apps]

Greptile Summary

The PR changes realtime policy-violation handling so active subscriptions receive an AppwriteException through their stream error channel rather than an uncaught exception from the websocket message callback.

• Broadcasts policy-violation errors to all active realtime subscription controllers.
• Bumps the package version to 26.1.0.
• Documents the fix in the changelog.

Confidence Score: 5/5

The PR appears safe to merge, with policy-violation failures now exposed through the subscription streams consumers can observe.

The changed handler preserves the existing exception type and distributes it through active broadcast stream controllers, while the package metadata and changelog consistently identify the 26.1.0 release.

Important Files Changed

Filename	Overview
lib/src/realtime_mixin.dart	Replaces an uncaught policy-violation throw with error delivery through each active subscription stream; no actionable defect was established.
pubspec.yaml	Updates the package version from 26.0.0 to 26.1.0 consistently with the release scope.
CHANGELOG.md	Adds a 26.1.0 entry accurately describing the realtime error-delivery fix.

_{Reviews (1): Last reviewed commit: "feat: deliver realtime policy-violation ..." | Re-trigger Greptile}