Add window size and position persistence

[Copilot]

Implements window geometry persistence to registry, matching native Notepad behavior.

Implementation

• State: Added windowX, windowY, windowWidth, windowHeight to AppState with 640×480 default
• Storage: New LoadWindowSettings() / SaveWindowSettings() functions write to HKEY_CURRENT_USER\Software\LegacyNotepad
• Lifecycle: Load on startup before CreateWindowExW(), save on WM_DESTROY using GetWindowPlacement().rcNormalPosition

Edge Cases

• Multi-monitor: Negative coordinates preserved via static_cast<int>(DWORD) round-trip
• Off-screen: MonitorFromRect() validation resets to CW_USEDEFAULT if no monitor intersection
• Maximized state: Uses rcNormalPosition so window doesn't reopen maximized unintentionally

Registry keys: WindowX, WindowY, WindowWidth, WindowHeight (REG_DWORD)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Remember window size and maybe position</issue_title>
<issue_description>Hello again!

Not really a bug or an issue but the og notepad remembers the window size and position of the last session. Since you already put font and always on top settings in the registry I guess this can be put there too?

Have a nice day and thanks!</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Remember window size and maybe position #20

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[Copilot]

Pull request overview

Adds persistence of the main window’s last normal position and size to the existing registry-backed settings system, so LegacyNotepad restores geometry across launches (similar to native Notepad).

Changes:

• Added window geometry fields (windowX, windowY, windowWidth, windowHeight) to AppState with defaults.
• Implemented LoadWindowSettings() / SaveWindowSettings() to read/write geometry under HKCU\Software\LegacyNotepad.
• Wired geometry load before CreateWindowExW() and geometry save on WM_DESTROY using GetWindowPlacement().rcNormalPosition.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/modules/settings.h	Exposes window settings load/save APIs.
src/modules/settings.cpp	Implements registry persistence for window X/Y/Width/Height and basic off-screen validation.
src/main.cpp	Loads geometry on startup; captures/saves geometry on shutdown; uses persisted geometry when creating the main window.
src/core/types.h	Extends AppState with persisted window geometry fields and defaults.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

[Copilot]

LoadWindowSettings() assigns registry REG_DWORD width/height directly to int after only checking > 0. If the stored DWORD exceeds INT_MAX, the cast can wrap to a negative int, which can make CreateWindowExW fail or create invalid geometry. Please bound-check the DWORDs (e.g., <= INT_MAX and within a reasonable min/max) before casting/assigning, and consider resetting to defaults when out of range.

[Copilot]

The RECT construction uses g_state.windowX + g_state.windowWidth and g_state.windowY + g_state.windowHeight in signed arithmetic. If registry values are large/corrupted, these additions can overflow int, which is undefined behavior in C++. Consider using a wider intermediate type and clamping to LONG range (or validating inputs) before building the RECT for MonitorFromRect().