[WIP] feature: VESA VBE 1.2

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Description of Changes

Implements VESA BIOS Extension (VBE) 1.2 support for the VGA BIOS, enabling Super VGA modes for games like Rules of Engagement 2. Addresses reviewer feedback from the initial implementation:

• BIOS-owned OEM string & mode list: VbeGetControllerInfo previously wrote OEM string and mode list beyond the caller's 256-byte buffer (overflow risk) and computed far pointers via (ushort)(DI + offset) (wraparound if DI ≥ 0xFF00). Now, InitializeVbeData() (called from constructor) writes both to fixed offsets within StaticFunctionalityTableSegment; VbeGetControllerInfo only writes the 256-byte VbeInfoBlock to ES:DI and sets far pointers to the BIOS-owned location.

• Complete mode list: VbeGetControllerInfo previously advertised only mode 0x102, while VbeGetModeInfo reported 23 modes as supported. The mode list now includes all 23 VBE 1.2 standard modes.

• Bit0Mask constant: Added BiosConstants.Bit0Mask = 0x01 for generic bit-0 checks. UpdateCursorPositionFlag (same value, cursor-specific semantics) is now used only where it describes cursor position updates; all other bit-0 tests (palette intensity, P5P4 select, gray scales, video enable, etc.) use Bit0Mask.

• Documentation fixes: VbeInfoBlock.Version comment no longer says "BCD format" (it's a binary field per spec). VesaFunctions summary corrected from "VBE 1.0" to "VBE 1.2". VbeConstants.Version12 comment updated to match.

Rationale behind Changes

Fixes correctness bugs (buffer overflow, pointer wraparound, incomplete mode enumeration) and improves maintainability (misnamed constant, incorrect doc comments).

Suggested Testing Steps

Already tested with Rules of Engagement 2.

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Pull request overview

This PR updates the INT 10h VESA VBE implementation in VgaBios toward VBE 1.2 compliance, primarily by moving OEM string + mode list into BIOS-owned storage to avoid caller-buffer overflow and pointer wraparound issues.

Changes:

• Store VBE OEM string and full 23-mode list in BIOS-owned memory and return far pointers to that storage from VbeGetControllerInfo.
• Expand the advertised mode list to match the modes already reported by VbeGetModeInfo.
• Introduce BiosConstants.Bit0Mask for generic bit-0 checks and fix several VBE/VGA-related doc comments.

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