🏗️ Extract tome from spire into standalone plugin

Tome is opt-in per project — each project declares its own knowledge
management approach. Spire retains a small knowledge-awareness skill
that explains what tome does and provides a fallback strategy for
projects without it.

- New plugins/tome/ with own manifests, README, all 5 sub-skills
- Spire keeps skills/knowledge/SKILL.md as awareness stub
- Updated all READMEs and marketplace JSONs
- tome: namespace refs now correct (tome is its own plugin)

README.md

@@ -8,7 +8,8 @@ The repo doubles as a **Claude Code marketplace** (`.claude-plugin/marketplace.j
 
 | Plugin | Description |
 |---|---|
-| ⚗️ [`spire`](./plugins/spire) | Agent orchestration system — session coordinator (Igor), domain knowledge agents (adepts), dispatching orchestrator (athanor), knowledge layer (tome), workpad, research tools |
+| ⚗️ [`spire`](./plugins/spire) | Agent orchestration system — session coordinator (Igor), domain knowledge agents (adepts), dispatching orchestrator (athanor), workpad, research tools |
+| 📖 [`tome`](./plugins/tome) | Knowledge layer — navigate, curate, check, handoff, init. Opt-in per project. Pairs with spire. |
 | 🧠 [`g4b_ai`](./plugins/g4b_ai) | *(Deprecated — use `spire`)* Core personal Claude Code skills |
 | 🐸 [`gitea`](./plugins/gitea) | Gitea issue tracker integration — fetch, create, close, and comment on tickets via self-contained `uv run` scripts |
 | 🦀 [`dioxus`](./plugins/dioxus) | Per-version API reference skills for the Dioxus Rust UI library (currently 0.7+) |
@@ -122,6 +123,7 @@ reliquary/
 │   └── marketplace.json           # Claude marketplace listing
 ├── plugins/
 │   ├── spire/                     # ⚗️ agent orchestration system
+│   ├── tome/                      # 📖 knowledge layer (opt-in)
 │   ├── g4b_ai/                    # 🧠 core skills (deprecated)
 │   ├── gitea/                     # 🐸 gitea issue tracker
 │   ├── dioxus/                    # 🦀 rust dioxus library reference