v0.19.1 — Streaming Stability & Thinking Animation Fix

Changes

🐛 Streaming Stability

• Overlap-tolerant chunk merging — new mergeStreamingChunk() handles cumulative snapshots, overlapping deltas, and exact replays from upstream without duplicating text
• Background session streaming — background Claude handler now uses the same merge logic, preventing text duplication when switching between sessions

🎨 Thinking Animation

• Extracted thinking animation state machine — moved from inline ThinkingBlock logic into a pure, testable thinking-animation.ts module
• Removed coalescing timer — the v0.19.0 interval-based chunk coalescing caused replay/duplication under rapid thinking updates; replaced with a simpler append-only model

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Full Changelog: v0.19.0...v0.19.1