✨ Spire plugin — MVP build (phases 1-3)

Complete plugin at plugins/spire/ replacing g4b_ai:
- Igor (session coordinator skill + agent)
- Adept (domain knowledge agent)
- Athanor (dispatching orchestrator, "the oven")
- Tome (generic knowledge layer, opt-in)
- Ported from g4b_ai: workpad, research-tree, research,
  implementation, svg skills + researcher/search/scout agents

All warpspace-specific content stripped. Tome genericized.
Project-specific config via shadowed project.md reference.

plugins/spire/skills/igor/references/journal-template.md

@@ -0,0 +1,23 @@
+# Journal Template
+
+```markdown
+# <Topic> — Assistant Session Journal
+
+**Date**: YYYY-MM-DD
+**Topic**: <session topic from invocation>
+**Worktree/branch**: <if any>
+
+## Log
+
+<!-- Append-only. One entry per dispatch/result/decision. -->
+
+- HH:MM — <what was dispatched / what came back / decision taken>
+
+## Artifacts
+
+<!-- Files produced this session, with paths. -->
+
+## Open threads
+
+<!-- Unfinished work, follow-ups, questions for the user. -->
+```