Preserve dictation's cursor-anchored insertion when the mic button steals focus

[davior]

Summary

Follow-up to #185, which shipped focusing the note editor's dictation mic button on start/stop (so Enter/Space toggles it). That had a regression: since the editor is no longer "focused" once the button has focus, insertDictatedText always fell back to appending dictated text at the end of the note, instead of inserting it wherever the user's cursor was — breaking "click anywhere in the note, then dictate at that position."

• insertBlocksAtCursor now accepts an optional anchor block id; when given and the block still exists, blocks are inserted after it regardless of the editor's current focus state.
• A new handleDictationToggle wrapper in EditorView.tsx captures the cursor's block synchronously, right before a dictation session starts — the last moment the editor still reports itself focused for that click, before focus moves to the mic button — and stores it in dictationAnchorBlockIdRef.
• insertDictatedText passes that captured anchor through for the session's first inserted block, so all subsequent chunks (which continue to merge into that same block via the existing dictationSessionBlockIdRef tracking) land in the right place.
• The anchor is cleared whenever a dictation session ends, alongside the existing session-block cleanup.

If dictation is started without the editor ever having had focus (e.g. clicking straight into the mic button), behavior is unchanged: it falls back to appending at the end of the note.

Test plan

• tsc --noEmit passes
• Manually verify: click into the middle of a note, start dictation, confirm dictated text is inserted at that cursor position (not appended at the end)
• Manually verify: start dictation without clicking into the note first, confirm it still appends at the end

🤖 Generated with Claude Code

https://claude.ai/code/session_019ssxort6KYBGuGLWikh3k4

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