docs: rebrand to Coi (drop all-caps COI; Coi primary, coi command) COI -> Coi across all pages; sidebar + Home first-mention use "Coi (Code on Incus)". Preserved: COI_* env-var names and the literal "# COI Sandbox ..." context markers (they document the actual on-disk marker text). Lowercase coi commands unchanged.
docs: split Supported Tools — extract Sandbox Context + Adding New Tools Supported-Tools.md mixed three audiences. Keep all per-tool sections together (users compare tools at a glance) and extract the two genuinely independent, cross-cutting sections into their own pages (page now ~11.5 KB / 272 lines, down from ~15.6 KB / 379 lines): - New **Sandbox Context** — the `~/SANDBOX_CONTEXT.md` / `.json` environment description, auto-context injection per tool, disabling it, and custom/JSON context files. It's referenced from Architecture and Configuration and isn't really about *which* tool. - New **Adding New Tools** — contributor docs: the `Tool` interface and optional capability interfaces (incl. ToolWithPrompt / ToolWithContainerEnv for `coi tool spec`) with worked examples. Supported-Tools keeps pointer stubs to both. Re-pointed the Configuration cross-reference to the new Sandbox Context page; credentials/permission-mode links stay valid (those sections remain). Added both pages to Home + _Sidebar (nested under Supported Tools). All internal links verified.