feat(skills): add setup-projects-meta + using-projects-meta pair

Wraps the local projects-meta-mcp stdio server with the validated split-pair
pattern (setup-X / using-X), 4th application after context7 / wiki / tasks.

setup-projects-meta — 8-phase install: clones server repo to
~/.local/projects-meta-mcp, builds, writes ~/.config/projects-mcp/auth.toml,
clones shared wiki to ~/projects/projects-wiki/ (canon path; legacy
~/projects/.wiki is detected and migrated — old path caused the
wiki-path-mismatch bug, fixed upstream in 621a69f), registers
mcpServers.projects-meta in ~/.claude.json. Confirmation gates between
discovery and writes.

using-projects-meta — runtime policy: read tools (tasks_aggregate,
knowledge_search, meta_status, ...) and mutation tools with mandatory
two-step preview→confirm. Carries the local-first rule inline: for the
current project read .tasks/ / .wiki/ from disk; MCP cache is for *other*
projects only.

Wiki concept page concepts/projects-meta-skills.md documents the design,
the path-canon fix, and the round-trip task lifecycle across machines.

Closes [projects-meta-skills] in claude-skills (created from
DESKTOP-NSEF0UK via projects-meta-mcp).

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

.wiki/index.md

@@ -16,6 +16,7 @@ Catalog of all wiki pages. One line per page, organized by type. Updated on ever
 - [build-notes.md](concepts/build-notes.md) — why `build.ps1` exists alongside `build.sh`; PS 5.1 backslash-in-zip gotcha; how to extract a `.skill`
 - [install-portability.md](concepts/install-portability.md) — `install.sh` / `build.sh` rewritten to drop `mapfile` (bash 4+) and `find -printf` (GNU only) so stock macOS (bash 3.2 + BSD find) works
 - [context7-setup.md](concepts/context7-setup.md) — switched context7 from manual MCP entries to the official plugin; API key in `.mcp.json` as `--api-key`; now also captured as `setup-context7` skill (one-time install/migrate flow with key discovery)
+- [projects-meta-skills.md](concepts/projects-meta-skills.md) — `setup-projects-meta` + `using-projects-meta` skill pair for the local `projects-meta-mcp` stdio server (cross-project tasks + shared Gitea wiki); local-first rule + two-step mutation pattern
 - [repo-layout.md](concepts/repo-layout.md) — flat `skills/`, committed `dist/`, bash + PowerShell scripts; install model
 - [skill-versioning.md](concepts/skill-versioning.md) — why infra skills carry `version: <semver>` in frontmatter and how `project-bootstrap` records them in a per-project manifest
 - [skill-vs-plugin.md](concepts/skill-vs-plugin.md) — when a bare SKILL.md is enough vs when you actually need a plugin (slash commands, hooks, sub-agents, MCP servers); concrete breakdown of `superpowers`