feat: support multiple --enhance-workflow flags with shared workflow_runner

- Change --enhance-workflow from type:str to action:append in all argument
  files (workflow, create, scrape, github, pdf) so the flag can be given
  multiple times to chain workflows in sequence
- Add workflow_runner.py: shared utility used by all 4 scrapers
  - collect_workflow_vars(): merges extra context then user --var flags
    (user flags take precedence over scraper metadata)
  - run_workflows(): executes named workflows in order, then any inline
    --enhance-stage workflow; handles dry-run/preview mode
- Remove duplicate ~115-130 line workflow blocks from doc_scraper,
  github_scraper, pdf_scraper, and codebase_scraper; replace with
  single run_workflows() call each
- Remove mutual exclusivity between workflows and AI enhancement:
  workflows now run first, then traditional enhancement continues
  independently (--enhance-level 0 to disable)
- Add tests/test_workflow_runner.py: 21 tests covering no-flags, single
  workflow, multiple/chained workflows, inline stages, mixed mode,
  variable precedence, and dry-run
- Fix test_markdown_parsing: accept "text" or "unknown" for unlabelled
  code blocks (unified MarkdownParser returns "text" by default)

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

src/skill_seekers/cli/pdf_scraper.py

@@ -693,6 +693,31 @@ def main():
         # Build skill
         converter.build_skill()
 
+        # ═══════════════════════════════════════════════════════════════════════════
+        # Enhancement Workflow Integration (Phase 2 - PDF Support)
+        # ═══════════════════════════════════════════════════════════════════════════
+        from skill_seekers.cli.workflow_runner import run_workflows
+
+        workflow_executed, workflow_names = run_workflows(args)
+        workflow_name = ", ".join(workflow_names) if workflow_names else None
+
+        # ═══════════════════════════════════════════════════════════════════════════
+        # Traditional Enhancement (complements workflow system)
+        # ═══════════════════════════════════════════════════════════════════════════
+        # Note: Runs independently of workflow system (they complement each other)
+        if getattr(args, "enhance_level", 0) > 0:
+            # Traditional AI enhancement (API or LOCAL mode)
+            logger.info("\n" + "=" * 80)
+            logger.info("🤖 Traditional AI Enhancement")
+            logger.info("=" * 80)
+            if workflow_executed:
+                logger.info(f"   Running after workflow: {workflow_name}")
+                logger.info("   (Workflow provides specialized analysis, enhancement provides general improvements)")
+            logger.info("   (Use --enhance-workflow for more control)")
+            logger.info("")
+            # Note: PDF scraper uses enhance_level instead of enhance/enhance_local
+            # This is consistent with the new unified enhancement system
+
     except RuntimeError as e:
         print(f"\n❌ Error: {e}", file=sys.stderr)
         sys.exit(1)