docs(iteration-system): collapse strategies/ into scanners/

Scanners and strategies are 1:1 in the current codebase — separate folder
was artificial. Each scanner file now captures both implementation and thesis.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/superpowers/specs/2026-04-07-iteration-system-design.md

@@ -44,17 +44,14 @@ docs/iterations/
 │   ├── ml_signal.md
 │   ├── minervini.md
 │   └── ... (one file per scanner)
-├── strategies/
-│   ├── analyst_upgrade.md
-│   ├── momentum.md
-│   ├── accumulation.md
-│   └── ... (one file per strategy pattern)
 ├── pipeline/
 │   └── scoring.md                      ← LLM scoring, confidence calibration, ranking
 └── research/
     └── YYYY-MM-DD-<topic>.md           ← web research findings (append-only, dated)
 ```
 
+Each scanner file captures both the implementation learnings and the underlying market thesis — no separate strategies folder since scanners and strategies are currently 1:1.
+
 ### Domain File Schema
 
 Each file in `scanners/`, `strategies/`, and `pipeline/` follows this structure: