refactor(wiki): migrate this repo's .wiki/ to canonical Karpathy layout

Stop being inconsistent with our own fixed project-bootstrap template.

- SUMMARY.md → index.md (catalog by type, with one-line hooks)
- source/*.md → concepts/*.md (with `git mv` so history is preserved)
- WORKFLOW.md removed (workflow lives in wiki-maintainer, not duplicated here)
- New: .wiki/CLAUDE.md (project schema, Karpathy gist URL pinned at top)
- New: log.md (append-only op log; backfilled with prior decisions)
- New: overview.md (single project intro page)
- New: raw/README.md (immutability note; replaces .gitkeep placeholder)
- Empty .gitkeep added to entities/, packages/, sources/
- Migrated pages got `type: concept` frontmatter

After this, wiki-maintainer reads .wiki/CLAUDE.md → index.md as it expects,
and the layout matches what newly-bootstrapped projects will look like.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.wiki/concepts/active-platform-decision.md

@@ -0,0 +1,45 @@
+---
+title: "Decision: active-platform skill"
+type: concept
+updated: 2026-04-28
+---
+
+# Decision: `active-platform` skill
+
+_2026-04-28._
+
+## Problem
+
+The user develops on multiple machines (Windows primary, Linux/macOS secondary). I was generating bash one-liners by default — wrong shell for their daily workstation. Need a way to make Windows/PowerShell the default and switch on a phrase.
+
+## Options weighed
+
+- **Project memory** — wrong scope (project-only, doesn't cross repos).
+- **Global `~/.claude/CLAUDE.md`** — right scope, simple, but the user explicitly preferred a skill: "поживём со скиллом" (let's live with a skill and iterate).
+- **New skill** ← chosen.
+
+The user's reasoning for the skill route: it's a discoverable, shareable artifact that lives next to their other 12 skills, and it can evolve with the same edit/build/install loop.
+
+## What the skill does
+
+Switches command/example generation between Windows / Linux / macOS based on session signals. Default = Windows + PowerShell. Trigger phrases in RU + EN (e.g. "мы на винде", "we're on Linux"). The rule applies only to **user-facing output** — tool calls still follow the harness's `Shell:` line.
+
+Full spec: [`skills/active-platform/SKILL.md`](../../skills/active-platform/SKILL.md).
+
+## Why this is a skill, not memory
+
+- **Discoverability:** appears in `available_skills` list, can be re-read or audited.
+- **Cross-repo:** installed into `~/.claude/skills/`, applies in every session regardless of project.
+- **Iterable:** lives in this repo's `skills/` so we can edit + reinstall as we learn what triggers and exceptions actually happen in practice.
+
+## Wired into `project-bootstrap`
+
+The default platform should travel with every new project we create. Updated `project-bootstrap` so its `CLAUDE.md.template` adds a fifth trigger line: `we're on Windows`. That line is one of `active-platform`'s recognized switches, so any project bootstrapped from now on starts pinned to Windows / PowerShell. If the user is bootstrapping on a Linux/macOS host, the `SKILL.md` Step 5 note tells them to swap the line for `we're on Linux` / `we're on macOS`.
+
+Backfilled the same line into this repo's own `CLAUDE.md` (which was created from the old template).
+
+## Open questions to revisit
+
+- Are the trigger phrases comprehensive enough? Add real-world examples as they come up.
+- WSL handling — currently treated as Linux. Reconsider if user has WSL-specific needs.
+- macOS divergences (BSD coreutils, Homebrew) — minimal coverage now, expand if user actually uses macOS often.