Add opt-in "Paste in Chunks" option for terminal AI agents (e.g. Claude Code)

[leochen4891]

Problem

When a long transcription is pasted into a terminal-based AI agent such as Claude Code, the destination collapses the single large paste into a placeholder (for example [Pasted text #N +M lines]) rather than showing it inline. The full text is still delivered, but the user cannot read or edit it before pressing Enter.

Before — a long dictation collapses into a placeholder:

After — with "Paste in Chunks" enabled, the same dictation lands as full, editable inline text:

Approach

Add an opt-in Paste in Chunks setting. When enabled, VoiceInk pastes the transcription in smaller pieces so each paste stays below the destination's collapse threshold, and the text renders as visible, editable inline text.

This mirrors the behavior Wispr Flow documents for Claude Code (auto-splitting long dictations into chunks).

It is a layer on top of the existing clipboard paste — a separate toggle plus chunk-size picker that composes with both the Default and AppleScript paste methods, rather than a new mutually-exclusive method. It is complementary to the Direct Typing work in #701: Direct Typing reaches destinations where the clipboard does not work at all (for example remote desktop), whereas chunking keeps a working clipboard paste from being collapsed.

Changes

• CursorPaster: the paste session now iterates over chunks with a short inter-chunk delay; splitting prefers whitespace and newline boundaries and falls back to a hard split for a single oversized run.
• Settings: new "Paste in Chunks" toggle and chunk-size picker (250 / 500 / 750 / 1000 characters).
• Defaults registered; off by default, so there is no behavior change unless enabled. Default chunk size is 250 characters.

[cubic-dev-ai]

3 issues found across 3 files

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[leochen4891]

Thanks for the review — addressed all three issues identified by cubic in 92b8d87:

1. Partial-paste success reporting — the paste loop now ANDs each chunk's result and returns success only when every chunk posts.
2. Clipboard left clobbered on mid-loop failure — a failed chunk now breaks out and still schedules the clipboard restore (using the last successfully prepared chunk).
3. O(n²) splitting — the splitter advances by index arithmetic instead of repeatedly reading count (which is O(n) on Swift strings).

Also added unit tests for the chunk splitter (ChunkSplittingTests) covering reassembly fidelity, max-length adherence, whitespace boundaries, hard-splitting an oversized run, multiline, non-positive lengths, and grapheme-cluster integrity.