feat: version infra skills (1.0.0) + project-bootstrap manifest step

Six infra skills carry `version: 1.0.0` in frontmatter:
project-bootstrap, setup-context7, task-status-wiki, using-context7,
using-markitdown, wiki-maintainer. Bumped manually on SKILL.md edits;
semver — MAJOR breaks contract, MINOR adds, PATCH wording.

project-bootstrap gets a new Step 5.5 that writes
.wiki/concepts/bootstrap-manifest.md per project — skill + version + role
table read live from each delegated skill's frontmatter, not hardcoded.
The file is overwritten on re-bootstrap; for history, git log.

Why: when canonical layout for .wiki/ or .tasks/ changes, projects
bootstrapped under the old version drift silently. The per-project
manifest makes that drift debuggable instead of guesswork. Communication
and discovery skills (caveman family, find-skills, active-platform)
aren't versioned — their content is "good copy-paste" and snapshot
mismatch isn't a layout problem.

Wiki: .wiki/concepts/skill-versioning.md documents the convention;
index.md and log.md updated. .tasks/STATUS.md tracks (a/b/c) progress.

Setup/using split for wiki and tasks (commits b and c) follows.

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

.wiki/log.md

@@ -22,3 +22,4 @@ Parseable: `grep "^## \[" .wiki/log.md | tail -20`.
 ## [2026-04-28] decision | setup-context7 skill — formalized the install/migrate algorithm; using-context7 gets a Prerequisites pointer; build.sh PS multi-arg bug fixed (loop instead of comma-joined -Names)
 ## [2026-04-28] verify | setup-context7 — Vitya ran using-context7 in a session that needed setup; Prerequisites pointer triggered setup-context7; full flow worked end-to-end. Pattern (policy + setup split) validated.
 ## [2026-04-28] decision | skill-vs-plugin — documented when a bare skill suffices vs when a plugin is required (slash commands, hooks, sub-agents, MCP via marketplace)
+## [2026-04-28] decision | skill-versioning — added `version: 1.0.0` to 6 infra skills' frontmatter; project-bootstrap now writes .wiki/concepts/bootstrap-manifest.md per project