feat: DX, extensibility, and adaptive intelligence — completes 25-feature backlog

Sprint 5 — Developer Experience (D1-D5):
- Progress indicators with emoji phase markers during orchestration
- Dry-run mode: preview workflow without executing
- /archeflow:status and /archeflow:history commands
- Onboarding skill for first-time users

Sprint 6 — Extensibility (E1-E4, A4-A6):
- Archetype composition: combine 2 archetypes into super-reviewer
- Team presets: save common team configs in .archeflow/teams/
- Hook points: pre-plan, post-check, pre-merge, post-merge custom validation
- Workflow template library: api-design, migration, dep-upgrade, docs, hotfix
- Reviewer profiles: per-project config of which reviewers run
- Explorer cache: skip redundant research on recently-explored code
- Learning from history: track archetype usefulness, recommend profile changes

skills/orchestration/SKILL.md

@@ -460,6 +460,51 @@ Each team follows the full PDCA steps independently. The orchestrator monitors a
 
 ---
 
+## Reviewer Profiles
+
+Projects can configure which reviewers matter in `.archeflow/config.yaml`:
+
+```yaml
+reviewers:
+  always: [guardian]        # Always runs
+  default: [sage]           # Runs in standard+thorough
+  thorough_only: [trickster] # Only in thorough
+  skip: [skeptic]           # Never runs for this project
+```
+
+If no config exists, use the built-in workflow defaults. Profiles save tokens by not spawning reviewers that add little value for the specific project.
+
+## Explorer Cache
+
+If the same code area was explored recently, skip Explorer and reuse prior research:
+
+**Cache hit criteria:** Same files affected (>70% overlap by path) AND prior research is <24 hours old AND no commits to those files since the research.
+
+**On cache hit:** Show the prior research to Creator with a note: "Using cached Explorer research from [timestamp]. If the codebase changed significantly, re-run Explorer."
+
+**On cache miss:** Run Explorer normally.
+
+Cache is stored in `.archeflow/explorer-cache/` as timestamped markdown files. The orchestrator checks for matches before spawning Explorer.
+
+## Learning from History
+
+Track which archetypes catch real issues per project over time. After each orchestration, append to `.archeflow/metrics.jsonl`:
+
+```json
+{"task": "...", "archetype": "guardian", "findings": 2, "critical": 1, "resolved": 2, "useful": true}
+{"task": "...", "archetype": "skeptic", "findings": 3, "critical": 0, "resolved": 0, "useful": false}
+```
+
+A finding is **useful** if it was resolved (led to a code change) rather than dismissed.
+
+After 10+ orchestrations, the orchestrator can recommend reviewer profile changes:
+- "Skeptic has found 0 useful issues in 8 runs — consider moving to `skip` or `thorough_only`"
+- "Guardian catches critical issues in 80% of runs — confirmed as essential"
+
+This is advisory, not automatic. The user decides based on the data.
+
+---
+
 ## Orchestration Report
 
 After completion, summarize: