🤖 Update init templates and supporting files for adept discovery

Rewrite init Phase 4: adepts/CLAUDE.md uses tiered conventions,
_template/CLAUDE.md becomes an index template with frontmatter, add
_template/handoff.md template. Update workpad skill with adepts/ folder,
project.md with roster reference, curator with adept scope note.

plugins/spire/skills/igor/references/project.md

@@ -11,7 +11,7 @@ preload) changes.
 
 - **Tome skill**: <!-- e.g. `my-project-tome:navigate` — or remove this line if the project has no tome skill. Igor will orient via direct file reads instead. -->
 - **Workpad**: <!-- Workpad location, e.g. `docs/workpad/` with its subfolder structure (goals/, plans/, reports/, research/, designs/, journals/, bugs/, specs/, archive/, adepts/). Reference the workpad's AGENTS.md or README for formatting rules. -->
-- **Adepts**: <!-- Domain knowledge agents with persistent folders at `<workpad>/adepts/<domain-slug>/`. See Igor skill's Adepts section for spawning/consulting conventions. -->
+- **Adepts**: Listed by `spire:adepts` at boot. Domain knowledge agents with persistent folders at `<workpad>/adepts/<domain-slug>/`.
 - **Pinned agents** (prefer these over generic tiers):
   <!-- List project-specific agents from `.claude/agents/` that should be preferred for certain task types. Example:
   - `my-researcher` — research/bug investigation, writes reports, never modifies code