✨ 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/project.md

@@ -0,0 +1,21 @@
+# Project Knowledge (per-project — swap this file when adopting Igor)
+
+Project-specific facts for Igor and the athanor. The generic behavior files
+stay unchanged across projects; only this file (and any tome/navigation skill
+preload) changes.
+
+## This project
+
+<!-- Replace the placeholder sections below with your project's specifics. -->
+
+- **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. -->
+- **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
+  - `my-implementer` — executes plans in the codebase
+  -->
+- **Verification commands**: <!-- e.g. `cargo check`, `npm test`, `make lint` — whatever confirms changes are correct. -->
+- **Domain skills to route to subagents when relevant**: <!-- e.g. `log-analysis` (crash logs), `my-framework` (before touching framework code). -->
+- **Conventions**: <!-- Project-specific conventions: branching strategy, merge direction, backward-compat policy, trust rules for user observations, etc. -->