Docs: assorted corrections and clarifications
Multiple documentation edits to correct values, clarify behavior, and tighten wording across the wiki. Notable changes: update installer/localization counts; clarify Backgroundog audio/timing fields and media-session semantics; add Cache subfolders (SignalT, Content) and cache details; fix memory unit reporting (GiB) and other unit notes; adjust many settings defaults (BackdropType=None, Update: Server=Soferity, Module=Downloader, Extension=Executable, AutoType default); document silent-uninstall is broken; refine engine/config filenames and mpv defaults; various UX/command/alias clarifications and minor wording fixes.
Add mermaid diagrams to architecture and internals docs
Embed mermaid flow/sequence diagrams across multiple documentation pages to visualize multi-process flows and lifecycle behaviour. Files updated: Architecture-Overview.md, Backgroundog-Service.md, Command-Reference.md, Crash-Reporting.md, IPC.md, Lifecycle.md, Undo-Internals.md, Update-Internals.md. Diagrams illustrate who-spawns-whom, Backgroundog lifecycle and data pump, command-bus flow, crash/reporting flow, IPC transports, cold-start sequence, uninstall removal sequence, and update pipeline. Improves developer clarity by providing visual references for existing textual descriptions.