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/workflow-design/SKILL.md

@@ -129,6 +129,112 @@ Check: Guardian
 Exit:  no_critical, max 1 cycle
 ```
 
+## Hook Points
+
+Add project-specific validation at key moments in the PDCA cycle. Define hooks in `.archeflow/hooks.yaml`:
+
+```yaml
+# .archeflow/hooks.yaml
+pre-plan:
+  - command: "npm run lint"
+    description: "Ensure clean baseline before planning"
+    fail_action: abort  # abort | warn | ignore
+
+post-check:
+  - command: "npm test"
+    description: "Run tests after review to verify reviewer suggestions"
+    fail_action: cycle_back
+
+pre-merge:
+  - command: "./scripts/check-migrations.sh"
+    description: "Verify migration safety before merging"
+    fail_action: abort
+
+post-merge:
+  - command: "npm run integration-test"
+    description: "Full integration test after merge"
+    fail_action: revert
+```
+
+**Available hook points:**
+| Hook | When | Typical Use |
+|------|------|-------------|
+| `pre-plan` | Before Explorer/Creator start | Lint, ensure clean baseline |
+| `post-plan` | After Creator's proposal | Validate proposal against constraints |
+| `pre-do` | Before Maker starts | Check worktree setup |
+| `post-do` | After Maker commits | Quick smoke test |
+| `post-check` | After reviewers finish | Run test suite |
+| `pre-merge` | Before merging to main | Migration safety, API compatibility |
+| `post-merge` | After merge completes | Integration tests, deploy checks |
+
+## Workflow Template Library
+
+Pre-built workflows for common scenarios. Use as-is or as starting points for custom workflows.
+
+### API Design
+```yaml
+name: api-design
+description: New or changed API endpoints
+plan: [explorer, creator]
+do: [maker]
+check: [guardian, skeptic]  # Guardian for security, Skeptic for API design assumptions
+exit: all_approved
+max_cycles: 2
+hooks:
+  post-check: "npm run api-compatibility-check"
+```
+
+### Database Migration
+```yaml
+name: migration
+description: Schema changes and data migrations
+plan: [explorer, creator]
+do: [maker]
+check: [guardian, db-specialist]  # Requires custom db-specialist archetype
+exit: all_approved
+max_cycles: 2
+hooks:
+  pre-merge: "./scripts/check-migration-reversibility.sh"
+```
+
+### Dependency Upgrade
+```yaml
+name: dep-upgrade
+description: Upgrading dependencies (major versions, security patches)
+plan: [creator]  # No Explorer needed — changelog is the research
+do: [maker]
+check: [guardian]
+exit: no_critical
+max_cycles: 1
+hooks:
+  post-do: "npm audit"
+  post-merge: "npm test && npm run e2e"
+```
+
+### Documentation Rewrite
+```yaml
+name: docs-rewrite
+description: Major documentation changes
+plan: [explorer, creator]
+do: [maker]
+check: [sage]  # Quality/consistency only — no security review needed
+exit: all_approved
+max_cycles: 1
+```
+
+### Hotfix
+```yaml
+name: hotfix
+description: Emergency production fix
+plan: [creator]
+do: [maker]
+check: [guardian]
+exit: no_critical
+max_cycles: 1
+hooks:
+  post-merge: "npm test"
+```
+
 ## Anti-Patterns
 
 - **Kitchen sink:** Putting all 7 archetypes in Check. Most can't add value simultaneously.