[Roxas2712]

Custom battle UIs currently need to replace native move-menu input code to choose grid navigation. This adds the public battle.move_grid_navigation predicate at the real move-selection controller, preserving the original opaque battle/screen handle across API 1/2 and API 3.

Only literal true selects the grid. The normal mode remains the default; Gen1 wide GB retains its fixed-grid bypass, and Gold-family wide mode accepts an explicit list override. The shared decision also controls Mimic selection. GBA doubles now clamp at row/column edges, correcting Gen2's previous generic wrapping to match Gen1's native doubles controller; DS retains its native grid behavior.

Stack

Depends on #152 and the earlier portability series. Feature-only comparison: 97eac55…3800b63. Earlier changes appear in the main-based diff until their prerequisites merge.

Validation

• Native navigation suite: 6,426/6,426 checks, all 15 Gen2-host games and four SDK modes, including defaults, wide layouts, Mimic, unsubscribe and wrapper recovery.
• The unchanged example runs through both real SDKs and native move controllers for Red, Yellow, Gold, FireRed and Emerald; API 1 native, API 2 native/unified and API 3 unified. Clean Gen1 reference: 79ea62f45fb2ea8f65d081a109431e4eb1bbdb36.
• Repeated on the feature commit and combined fork runtime: 80 workers / 3,840 paired navigation observations.
• Feature quick run: 105/115 engine suites, with exactly the same ten baseline failing suites and failure lines as Add portable auxiliary battle menu actions and shared native contracts #152; SDK 3/3 and B30 pass.
• Combined fork runtime c24e3a2f9987e1f420ed81a79c7f1e7caf61df72: 160/160 engine suites, SDK 3/3, B30 pass.
• Unmodified Gen1 native hook suites: 645/645 and 2,004/2,004.
• Native LÖVE 11.5 boot smoke tests reach intro/title/New Game for Red, Gold, FireRed and Emerald in an isolated identity. These are startup checks, not full playthroughs or GPU pixel goldens.
• Workflow passes actionlint; shared consumer, native fixtures, checker and contract documentation are included.

Hosted CI: all 14 PR workflows currently report action_required and await maintainer approval. The new battle-grid run has zero executed jobs. The passing results above are local validation.