🤖 Align Igor with the lean build cycle

Adds the attack-the-plan step and per-phase review to the development
cycle, the fix-pass stop rule, Athanor resume between phases, and the
alias-over-pin model rule. Drops the stale 4.6-for-implementation
guidance and per-task review convention. Harness notes now point to the
implementation skill's spawning reference.

plugins/spire/README.md

@@ -17,7 +17,7 @@ Replaces `g4b_ai`.
 | `workpad` | Document placement — reports, plans, goals, brainstorms, designs, journals, research, specs. |
 | `research-tree` | Multi-topic research as a dependency tree of parallel phases. |
 | `research` | Research governance — bounded agent spawning, web fetch budgets. |
-| `implementation` | Implementation orchestration — sequencing, delegation, verification. |
+| `implementation` | Lean implementation — attack the plan against the code, build in phases, one review per phase. |
 | `svg` | SVG diagram placement and referencing in markdown. |
 
 ### Agents
@@ -26,7 +26,7 @@ Replaces `g4b_ai`.
 |-------|------|
 | `igor` | Session coordinator (loaded by the igor skill). |
 | `adept` | Domain-scoped knowledge agent. Long-lived within a session, accumulates journals. |
-| `athanor` | Dispatching orchestrator — the slow furnace. "Put it in the oven." |
+| `athanor` | Build furnace (Opus 5.5) — builds a reshaped plan one phase per turn. "Put it in the oven." |
 | `researcher` | Deep research. Reads, synthesizes, writes reports. No sub-agents. |
 | `search` | Read-only code/file lookup. |
 | `scout` | Lightweight fact extraction. Fast and cheap. |