Add shared cheats and target discovery tools

[jiangxincode]

Summary

Adds a shared cheat system to native32emu-core and exposes it through both supported frontends: standalone CLI rules and RetroArch's emulator-handled cheat interface. The PR also adds standalone-only target discovery/filtering tools, verifies game-specific codes for EBBLADE, EGUNFIRE, EMETAL, and ESTORM, and reorganizes the frontend documentation around complete standalone and RetroArch guides.

Implementation

Shared cheat engine

• Adds CheatManager, indexed cheat slots, rule parsing, enable/disable state, reset behavior, and per-frame application in native32emu-core.
• Applies enabled rules after normal game logic on every emulation tick so locked values are restored consistently.
• Keeps cheat rule parsing and application frontend-independent so standalone and libretro use the same code strings and runtime behavior.
• Supports these rule forms:
  • var:<name>=<value> for VM variables.
  • sprite:<name>.<field>=<value> and movie:<name>.<field>=<value> for x, y, depth, frame, visible, and playing.
  • frame:goto=<n> for main-timeline jumps.
  • frame:playing=<bool> for main-timeline play/pause state.
• Accepts 1/0, true/false, on/off, and yes/no for boolean fields.

Standalone integration

• Adds repeatable --cheat <RULE> arguments.
• Logs and ignores malformed CLI rules instead of aborting game startup.
• Adds --debug-cheats to periodically list the current timeline, VM variables, and sprite targets.
• Adds --cheat-debug-interval <N> with a default interval of 30 frames.
• Adds --cheat-debug-filter <GLOB> to filter variable names with case-sensitive * and ? matching, for example p_*.

RetroArch integration

• Implements retro_cheat_set with indexed slots and enabled state.
• Implements retro_cheat_reset to clear all core-managed cheats.
• Uses RetroArch's Emulator cheat handler so rule strings are passed to the core rather than interpreted as frontend memory-address cheats.
• Keeps cheat target discovery out of the RetroArch core options to keep the core UI and documentation simpler; target discovery is supported only by the standalone emulator.
• Reapplies normal core option changes live without reloading content.

Target discovery

• Standalone-only discovery logs sorted VM variables and sprite state, capped at 64 entries per category with omitted-entry counts.
• Includes current frame, playback state, sprite movie/frame/position/depth/visibility/playback state, and pending frame information.
• Preserves filtering configuration when debug logging settings are updated.
• Adds focused tests for target formatting, debug configuration, and glob matching.

Verified game codes

EBBLADE (Blades of Red / 赤刃) was tested with player-variable filtering. p_hp was observed dropping from 96 to 88 after damage, then remaining at 96 when this rule was enabled:

var:p_hp=96

EGUNFIRE (Gun Fire / 枪火) was tested by directly loading NA32SSL/ENGLISH/GUNFIRE/GUNF1.SSL for target discovery. he_l was observed dropping from 104 to 100 without cheats, then remaining at 104 through 720 ticks when this rule was enabled:

var:he_l=104

The score rule was also verified through debug output and displayed score sprites:

var:he_score=999999

EMETAL (Metal Storm / 钢铁风暴) target discovery found pl_hp in NA32SSL/ENGLISH/METAL/MSPLAY10.SSL. The documented rule keeps the player health variable at its observed maximum:

var:pl_hp=60

ESTORM (Storm / 风暴之翼) was tested through NA32SSL/ENGLISH/STORM/STPLAY10.SSL. Target discovery identified player health, lives, bombs, and score variables; the enabled rules kept these values fixed through the verification run:

var:p_hp=9
var:p_life=9
var:p_bomb=9
var:p_score=999999

The verified codes are recorded in docs/Cheat-Codes.md. Cheat codes are shared by the standalone emulator and RetroArch core; only target discovery is standalone-only.

Documentation

• Replaces the narrow options-only documents with complete frontend guides:
  • docs/Standalone-Emulator.md
  • docs/RetroArch-Core.md
• Moves ZIP/FHUI menu and ESC behavior into the standalone guide.
• Moves RetroArch installation, supported features, RetroPad mapping, core options, and emulator-handled cheat setup into the RetroArch guide.
• Keeps docs/Cheat-Codes.md focused on verified codes grouped by game for future expansion.
• Adds EBBLADE, EGUNFIRE, EMETAL, and ESTORM cheat codes to the game-code list.
• Simplifies README usage and keeps shared audio capabilities in the main feature list.
• Updates website footer links and labels for the renamed guides.

Validation

• cargo test --all
• cargo clippy -- -D warnings
• cargo fmt -- --check
• cargo check -p native32emu
• cargo check -p native32emu-libretro
• cargo run -p native32emu -- --help
• Manual EBBLADE target-discovery and var:p_hp=96 lock verification
• Manual EGUNFIRE target-discovery, var:he_l=104 lock verification, and var:he_score=999999 score verification
• Manual EMETAL target-discovery for var:pl_hp=60
• Manual ESTORM target-discovery and var:p_hp=9, var:p_life=9, var:p_bomb=9, var:p_score=999999 verification

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jiangxincode]

libretro/libretro-super#2005