feat: capture active meeting chat into memos

[ComputelessComputer]

Summary

• Adds an AX read-side meeting chat capture command for supported active Zoom and Slack meeting surfaces.
• Appends captured chat entries into the active session's Memos as source-prefixed paragraphs with sender/timestamp metadata when available.
• Dedupes captured chat against in-memory signatures and existing memo text to avoid repeats after rescans or reconnects.
• Regenerates detect plugin bindings and permission metadata for the new command.

Notes

This builds on the AX meeting surface work from #5808, so this PR currently includes that dependency in its commit history.

Validation

• pnpm exec dprint fmt
• pnpm -F desktop typecheck
• pnpm -F desktop exec vitest run src/stt/useStartListening.test.ts
• cargo test -p detect meeting_ax -- --nocapture
• cargo check -p detect -p tauri-plugin-detect

Full cargo check was attempted but hung in swift-package resolve for crates/transcribe-soniqo/swift-lib, so it was interrupted and replaced with scoped Rust checks for the changed crates.

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