refactor: restructure specs and plans directories

- Specs (brainstorming output) now go to docs/superpowers/specs/
- Plans (writing-plans output) now go to docs/superpowers/plans/
- User preferences for locations override these defaults
- Update all skill references and test files

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

skills/brainstorming/SKILL.md

@@ -78,7 +78,8 @@ digraph brainstorming {
 ## After the Design
 
 **Documentation:**
-- Write the validated design to `docs/plans/YYYY-MM-DD-<topic>-design.md`
+- Write the validated design (spec) to `docs/superpowers/specs/YYYY-MM-DD-<topic>-design.md`
+  - (User preferences for spec location override this default)
 - Use elements-of-style:writing-clearly-and-concisely skill if available
 - Commit the design document to git
 

skills/requesting-code-review/SKILL.md

@@ -58,7 +58,7 @@ HEAD_SHA=$(git rev-parse HEAD)
 
 [Dispatch superpowers:code-reviewer subagent]
   WHAT_WAS_IMPLEMENTED: Verification and repair functions for conversation index
-  PLAN_OR_REQUIREMENTS: Task 2 from docs/plans/deployment-plan.md
+  PLAN_OR_REQUIREMENTS: Task 2 from docs/superpowers/plans/deployment-plan.md
   BASE_SHA: a7981ec
   HEAD_SHA: 3df7661
   DESCRIPTION: Added verifyIndex() and repairIndex() with 4 issue types

skills/subagent-driven-development/SKILL.md

@@ -93,7 +93,7 @@ digraph process {
 ```
 You: I'm using Subagent-Driven Development to execute this plan.
 
-[Read plan file once: docs/plans/feature-plan.md]
+[Read plan file once: docs/superpowers/plans/feature-plan.md]
 [Extract all 5 tasks with full text and context]
 [Create TodoWrite with all tasks]
 

skills/writing-plans/SKILL.md

@@ -15,7 +15,8 @@ Assume they are a skilled developer, but know almost nothing about our toolset o
 
 **Context:** This should be run in a dedicated worktree (created by brainstorming skill).
 
-**Save plans to:** `docs/plans/YYYY-MM-DD-<feature-name>.md`
+**Save plans to:** `docs/superpowers/plans/YYYY-MM-DD-<feature-name>.md`
+- (User preferences for plan location override this default)
 
 ## Bite-Sized Task Granularity
 
@@ -98,7 +99,7 @@ git commit -m "feat: add specific feature"
 
 After saving the plan, offer execution choice:
 
-**"Plan complete and saved to `docs/plans/<filename>.md`. Two execution options:**
+**"Plan complete and saved to `docs/superpowers/plans/<filename>.md`. Two execution options:**
 
 **1. Subagent-Driven (this session)** - I dispatch fresh subagent per task, review between tasks, fast iteration