docs(wiki): initial 18-page technical documentation
Populates the Rusty2600 GitHub Wiki with real, authored technical content
mirroring RustyNES's own wiki structure where a genuine analog exists,
adapted for the Atari 2600's different architecture:
- Home, Getting-Started, Building-from-Source, Roadmap, Deferred-Features
- Architecture-Overview, Lockstep-Scheduler, CPU-6507, TIA (video AND
audio -- the TIA owns both, unlike consoles with a separate video chip
and sound chip), RIOT (no NES analog; the console's only RAM + I/O +
timer), Cart-Catalogue (the closed 26-scheme bankswitch catalogue)
- Frontend-Architecture, Netplay-and-Rollback, Scripting-Engine,
Testing-Strategy
- Mobile-and-Cross-Platform
- Architecture-Decision-Records, Reference-Materials
Every technical claim is grounded in the current state of docs/, docs/adr/,
CLAUDE.md, and the crate source -- cross-checked against docs/STATUS.md as
the authoritative source where other docs (e.g. docs/compatibility.md's
stale Curated/BestEffort tier counts) disagreed.