docs: sync GemminiBall, Verilator, and build system documentation

[cursor]

This PR adds comprehensive documentation for recent Buckyball changes:

New Documentation

1. GemminiBall Architecture (content/*/Guide/GemminiBall Architecture.md)

   • Architecture overview and core modules
   • Instruction routing by funct7 (recent encoding update)
   • Execution paths and configuration registers
   • ROB tracking and integration with Buckyball

2. Verilator Simulation and CI (content/*/Guide/Verilator Simulation and CI.md)

   • Clock and timing improvements (rising-edge detection, mmio_tick debouncing)
   • Memory section handling in BBSimHarness
   • Running tests and CI pipeline configuration
   • Debugging waveforms and troubleshooting

3. Development Workflow and Build System (content/*/Guide/Development Workflow and Build System.md)

   • Nix Flakes setup and development environment
   • bbdev tool usage and Verilator simulation
   • Code organization and subsystem overview
   • Common development tasks and testing

Coverage

• Codepaths: arch/framework/balldomain/prototype/gemmini/, sims/verilator/, build system
• Recent commits: GemminiBall features, instruction encoding updates, Verilator config fixes, bbdev updates

Both English and Chinese documentation are included.

  

[shirohasuki]

No checks have been carried out to ensure that recent commits have not rendered parts of the existing documentation out of date
Recent commits regarding Goban are missing