docs: update the wiki to the source-build reality The patch-system pages described the retired era (patches/, the VSCodium archive, apply-picode.ps1). Architecture, Building, CI, Distribution and Roadmap are rewritten from the canonical docs; the Glossary, Getting PiCode and Home lose the stale references; The Patch System becomes a tombstone. The agent layer is described as it is now: native chat modified in the core over pi.
docs: seed the wiki with everything the repository knows Thirteen pages in English, synthesized from docs/, the 34 odd/tasks records and the verified session memory: what PiCode is, getting it, the first-run wizard, architecture, the source build, the patch system, Pi inside, Gentle AI and ODD, distribution and licensing, CI and releases, the ADR index, roadmap and known state, and a glossary. Mirror of the repository's wiki/ folder.