River Raid display integration, version 22

The original 4 KB cartridge is preserved alongside a one-byte modified copy.
The loaded copy changes SBC #$20 at file operand offset 1598 to SBC #$10,
exactly halving fuel drain. Refueling and other instructions are unchanged.
The base Javatari release is unchanged. trace-tia.js and
trace-monitor.js extend the Javatari 5.0.4 sources under AGPL-3.0 with an independent
read-only raster sidecar. The sidecar has no writes to game RAM, CPU, timing,
audio or collision state. Metadata follows GRP1 vertical-delay latches and the
actual indirect ROM sprite pointers, including shared bytes and interlacing.
The modern renderer reads that sidecar; the original renderer remains selectable.

Original Javatari source and license are separately hosted as source.zip and
license.txt in this same directory. The modified sources and readable rendering
code are included here. No build is required to run them.

Cartridge: MD5 393948436d1f4cc3192410bb918f9724
Original source: https://github.com/ppeccin/javatari.js
RAM and ROM analysis reference: Thomas Jentzsch, River Raid disassembly (2001),
https://github.com/johnidm/asm-atari-2600/blob/master/riverraid.asm

Validation:
- 1,800 synchronized frames: original and observed emulation states/video match.
- 3,600 additional synchronized frames, including original-game refueling.
- Sprite bounds verified against the cartridge geometry; enemy jet fixture checked.
- Local browser: restart, original/modern toggle, landscape and sprite rendering.

Native explosion effects and unsupported hardware patterns are retained verbatim.

Version 22: cached object sprites, 4x2 rather than 6x6 render surface, and
hoisted observational TIA RAM reads. ROM and population tables unchanged.
bridge-rules.js is an explicit gameplay extension: at the verified cartridge
collision-dispatch instruction (offset 1715), the first two bridge missile hits
consume the shot and skip target destruction/scoring. The third runs the native
explosion and scoring path. Non-bridge targets are untouched. Resets clear damage.
Modern display adds cracks and eight staggered falling bridge fragments/splashes.
Validation: 1800 native/observed lockstep frames; actual CPU three-hit collision
test checks survival, consumed missiles, score, explosion, reset and other targets.
