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/custom-archetypes/SKILL.md

@@ -138,9 +138,68 @@ Agent(
 
 Or in a custom workflow, include them in the check phase archetypes list.
 
+## Archetype Composition
+
+Combine two archetypes into a focused super-reviewer when you need a specific perspective but don't want to spawn two agents:
+
+```markdown
+# .archeflow/archetypes/security-breaker.md
+
+## Identity
+**ID:** security-breaker
+**Composed of:** Guardian + Trickster
+**Role:** Security review with active exploitation attempts
+**Lens:** "Can I break the security model? How?"
+**Model tier:** standard
+
+## Behavior
+Combine Guardian's checklist-driven security review with Trickster's
+adversarial testing. For each Guardian finding, attempt to exploit it.
+Only report findings you can actually reproduce.
+
+## Shadow
+**Name:** Security Theater
+**Strength inverted:** Both shadows compound — paranoid blocking + noise
+**Correction:** "Only report findings with reproduction steps. Max 5."
+```
+
+**Rules for composition:**
+- Max 2 archetypes combined (more defeats the purpose)
+- Combined shadow must address both source shadows
+- Use when spawning both separately would waste tokens on overlapping context
+
+## Team Presets
+
+Save common team configurations for your project in `.archeflow/teams/`:
+
+```yaml
+# .archeflow/teams/backend.yaml
+name: backend
+description: Standard backend development team
+plan: [explorer, creator]
+do: [maker]
+check: [guardian, sage]
+exit: all_approved
+max_cycles: 2
+```
+
+```yaml
+# .archeflow/teams/security-audit.yaml
+name: security-audit
+description: Security-focused review team
+plan: [explorer, creator]
+do: [maker]
+check: [guardian, trickster, compliance-auditor]
+exit: all_approved
+max_cycles: 3
+```
+
+Use in orchestration: `"Use the backend team preset"` or `"Run security-audit workflow on this change"`
+
 ## Design Principles
 
 1. **One concern per archetype.** Don't make a "full-stack reviewer."
 2. **Concrete shadow.** Vague shadows don't get detected. Use observable symptoms.
 3. **Right model tier.** Analytical → cheap. Creative → standard. Judgment-heavy → premium.
 4. **Specific lens.** The one question the archetype asks. This focuses behavior.
+5. **Composition over sprawl.** Combine before creating from scratch. 2 composed > 3 separate.