Pace Windows streaming SendInput

[H-Chris233]

User description

Summary

• Add Windows streaming SendInput pacing to unicode_keystroke::type_unicode_chunk.
• Match the existing non-streaming Windows pacing: 16 chars per chunk, 12ms between chunks.
• Keep the fix scoped to Claude's high-risk [windows][bug] 录音结束后总会出现明显的约5s卡顿 #491 finding; no IME, clipboard, or hotkey behavior changes.

Test Plan

• git diff --check
• cargo test --manifest-path "/home/chris233/openless/openless-all/app/src-tauri/Cargo.toml" unicode_keystroke
• cargo test --manifest-path "/home/chris233/openless/openless-all/app/src-tauri/Cargo.toml" streaming_insert
• cargo check --manifest-path "/home/chris233/openless/openless-all/app/src-tauri/Cargo.toml" --target "x86_64-pc-windows-gnu"

Refs #491

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PR Type

Bug fix

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Description

• Pace Windows SendInput batches

• Insert short delays between chunks

• Reduce post-recording input stalls

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Diagram Walkthrough

flowchart LR
  A["Windows unicode typing"] -- "processes characters" --> B["Chunked SendInput batches"]
  B -- "sleep after 16 chars" --> C["Reduced input contention"]
  C -- "prevents" --> D["Post-recording UI freeze"]

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File Walkthrough

	Relevant files
Bug fix	unicode_keystroke.rs Add paced Windows Unicode input sending                                    openless-all/app/src-tauri/src/unicode_keystroke.rs Adds Windows-specific pacing constants for SendInput chunk size and delay. Switches Unicode typing to track chunk progress while iterating characters. Sleeps briefly after every 16 characters when more input remains. +12/-1

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[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis 🔶 491 - Partially compliant Compliant requirements: Windows SendInput batching is now paced in 16-character chunks with a 12ms delay. The change is limited to the Windows Unicode typing implementation. Non-compliant requirements: Actual elimination of the reported post-recording stall cannot be confirmed from code review alone. Requires further human verification: Verify on a Windows machine that the ~5s post-recording freeze is gone in the reported scenarios. Confirm that the added pacing does not noticeably regress normal typing latency for larger inserts.

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ No major issues detected