[Roxas2712]

A source field renderer could not enter the native GBA world draw phase. This adds that boundary and a default terrain/actor capture over the admitted native world, with owned source atlases, explicit viewports and the native actor/effect state. Rendering does not construct another world or advance another simulation clock.

True 16px room boundaries remain separate from even layout storage padding. Connected pairs retain their own atlases; stationary batches rebind palette/animation uploads. Native and source drawing share integer Flash scanlines. Capture options, camera panning, graphics-state fencing and resource retirement are explicit. The existing native GraphicsScope guard is reused because it is absent from the public base.

Stacked on #291; the new review units are 8d33d66 and 7ab8d41. The separately offered map/palette/atlas prerequisites (#240, #245, #246, #250, #251, #259, #260) and native player/session facade (#254, #265) are reused. This does not replace a missing native stack with a simulated world. Fork persistent-world map admission is a separate follow-up.

Validation:

• Fork integration: PR Roxas2712/Gen2Recomped#71 merged. Combined main 96a39a0 passes 451/451 engine suites and 3/3 SDK suites; feature CI 69 successful, one unchanged-target iOS skip.
• Actual fork GPU hosts: LÖVE 11.5 OpenGL and LÖVE 12 OpenGL/Metal, each 187 checks, 110 image comparisons and 135 readbacks across all five GBA editions, three viewports, panning, palette reload and upload-buffer rotation. Independent pinned scanline comparison: 5,025 cases match.
• Actual public API-2 prerequisite composition: 256 field + 6 Flash checks, SDK 3/3, and the same 187 GPU checks/110 comparisons on LÖVE 12 OpenGL and Metal. Baseline and candidate retain exactly the same 35 failure lines across 15 existing engine suites; this is not an all-green public engine result. The extra prerequisite failures include palette/import fixture issues and are recorded separately from the earlier smaller baseline.
• Unchanged original-package entry advances past field_view in every GBA edition and stops at the next missing battle interface. Full initialization/gameplay, original effect-task/art/timing parity, source-specific mosaic/order/void-fade behavior and iOS/Android/Switch acceptance remain open.

Contribution permission and credit: Roxas2712 contribution licence. Existing third-party rights and notices remain effective.