[Roxas2712]

The native GBA battle path still uses the older byte accuracy/secondary model. This changes bounded RNG consumption, accuracy-stage arithmetic and public hook behavior; Thunder draws its post-hit chance in 0..255 rather than the native 0..99.

Add private native accuracy and secondary commands for GBA while preserving older-game behavior. Accuracy covers combined stages, ability/item floors, all-slot weather suppression, Protect/semi-invulnerability, native guaranteed-hit guards, absorption and the public battle.accuracy context. The ordinary secondary family shares native draw ordering, inclusive chance boundaries (including explicit zero), Serene Grace and effect-level guards. Authored effect handlers retain their policies. Real special Fire hits thaw after secondary processing; Substitute hits do not.

Preserve native strong-poison identity through API-3 reads/callback edits, battle construction, save serialization and party transport using the existing PSN plus boolean toxic marker. Bound callback edits update the owning toxic counter transactionally.

This stacks on #214 and its prerequisites. The Gen1 reference remains unchanged and read-only.

Validation on clean feature a6205dfce1b6d091e758238447db3b25462367f4:

• 15,082 accuracy + 53,598 secondary + 156 protocol checks pass (68,836 total).
• All 72 workers / 48,524 paired observations match unchanged reference 535a5ec088c1ae1bf4d91dd3e35a56f64cf46d91. The checker executes the actual reference commands and both move resolvers; every bounded RNG call/value, callback context, PP/HP/stage result and status event is retained.
• Full ROM-free run: 98/107 engine suites, SDK 3/3 and B30 pass. The exact Counter of all 25 inherited FAIL lines across nine suites equals clean Create native Gen-3 preset parties with consistent identities #214 (95/104). The combined fork already carries their separate repairs.
• Clean pre-secondary 184fdaaa retains 56 differing Thunder execution observations in the negative control; failing reports are preserved.
• A CPU-only smoke runs imported Thunder through the public enemy-action/status-event path using actual local FireRed/Emerald records. Both profiles hit and apply paralysis using native ranges. No imported data/assets/saves are committed.
• Scoped StyLua, actionlint and whitespace checks pass.

Link compatibility: add native GBA command revision 1 and hash native move index/effect, secondary chance, target, flags and Protect eligibility. Cache keys include runtime revision. Non-GBA fixture digests stay unchanged; no golden is reblessed. The audited raw GBA fixture changes from e33d251961f2a41d to 3a76cc5fce47a5c3. Actual handshake/controller tests stop older peers before battle, cover both roles and field mutations, and complete two seeded synthetic link mirrors with matching turn hashes/components and toxic markers.

Scope: this establishes command, hook and toxic-marker contracts. Full cartridge genetics transport, timed Lock-On/side/volatile producers, whole-game RNG/VBlank scheduling and demo controller playback remain separate. CPU fixtures do not certify live rendering or a full playthrough. See docs/native-gen3-hit-commands.md for reproducible commands and limits.

Combined fork acceptance: runtime 4a2f0d15de9820e897f6dfe895e204b3737a15d6 passes 222/222 engine suites, SDK 3/3 and B30. Its clean checkout also matches all 72 workers / 48,524 paired observations, and the actual imported FireRed/Emerald Thunder smoke passes on that runtime. The documented snapshot is pushed as f398caec15f2c8547a15c3928298f99ce2036057 to Roxas2712/Gen2Recomped:codex/portability-testing. Fork main stays at 13af468b.

All seven hosted workflows require maintainer approval (action_required). The dedicated contract run has zero jobs; local green acceptance does not claim hosted execution. The app's 100-artifact limit prevented an additional PR attachment; the regular PR is published and linked.