fix(windows): eliminate console window flashes using PseudoConsole

[scrossle]

Summary

Fixes #20. On Windows 11 / Windows Terminal, every hook execution caused a visible console window flash (popup). This was because npx spawned through shell: true allocated a new console window.

This PR replaces the simple npx wrapper (silent-npx.js) with a three-part solution:

• PseudoConsole (ConPTY) + CREATE_NO_WINDOW: A C# launcher (SilentLauncher.cs) compiled as a winexe creates a headless PseudoConsole session. Scripts run inside this invisible console — no popup.
• Single-process tsx execution: Uses --import tsx/esm as a Node.js ESM loader instead of the tsx CLI (which spawns a child process). Combined with --require stdio-preload.cjs, stdin/stdout flow through temp files so the PseudoConsole doesn't need STARTF_USESTDHANDLES (which re-triggers the flash on Win11 26300).
• Background worker survival: Workers (for async Letta API calls) spawn through silent-launcher.exe with detached: true. Since the exe is a winexe, detached doesn't create a console flash, and workers get their own PseudoConsole so they survive the parent's closure.

Additional fixes included

• Letta API message ordering: The /conversations/{id}/messages endpoint does not guarantee newest-first ordering. Added explicit date sorting so lastSeenMessageId tracking works correctly.
• API limit: Bumped message fetch limit from 50 to 300 — Letta returns multiple entries per logical message (hidden_reasoning + assistant_message pairs), so 50 was insufficient for active conversations.

Files changed

File	Description
hooks/SilentLauncher.cs	New — C# source for the PseudoConsole launcher
hooks/silent-launcher.exe	New — Compiled binary (AnyCPU winexe, works on x64 and ARM64)
hooks/stdio-preload.cjs	New — Node.js --require script for temp file stdin/stdout
hooks/silent-npx.cjs	New — Cross-platform shim: delegates to silent-launcher.exe on Windows, runs tsx directly elsewhere
hooks/silent-npx.js	Deleted — Replaced by .cjs version (required since package.json has "type": "module")
hooks/hooks.json	Modified — .js → .cjs extension
scripts/sync_letta_memory.ts	Modified — Date sorting, limit bump, Windows worker spawn
scripts/send_messages_to_letta.ts	Modified — Windows worker spawn

Non-Windows impact

No behavior change on Linux/macOS. The new silent-npx.cjs falls back to running tsx directly (same as before, just without the npx indirection).

Test plan

• Verified no console popups across 6+ hook firing cycles on Windows 11 ARM64 (build 26300)
• Verified bidirectional Letta message sync (messages TO and FROM Subconscious)
• Verified background workers survive main script exit
• Verified lastSeenMessageId advances correctly (no duplicate messages)
• Needs testing on x64 Windows
• Needs testing on Linux/macOS (should be no behavior change)

Supersedes #21.

🤖 Generated with Claude Code

[Abeansits]

@cpfiffer rdy to merge this? 🙏