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/arguments/create.py

@@ -16,9 +16,10 @@ from skill_seekers.cli.constants import DEFAULT_RATE_LIMIT
 from .common import RAG_ARGUMENTS
 
 # =============================================================================
-# TIER 1: UNIVERSAL ARGUMENTS (15 flags)
+# TIER 1: UNIVERSAL ARGUMENTS (19 flags)
 # =============================================================================
 # These arguments work for ALL source types
+# Includes: 11 core + 4 workflow + 4 RAG (merged from common.py)
 
 UNIVERSAL_ARGUMENTS: dict[str, dict[str, Any]] = {
     # Identity arguments
@@ -112,6 +113,38 @@ UNIVERSAL_ARGUMENTS: dict[str, dict[str, Any]] = {
             "metavar": "FILE",
         },
     },
+    # Enhancement Workflow arguments (NEW - Phase 2)
+    "enhance_workflow": {
+        "flags": ("--enhance-workflow",),
+        "kwargs": {
+            "action": "append",
+            "help": "Apply enhancement workflow (file path or preset: security-focus, minimal, api-documentation, architecture-comprehensive). Can use multiple times to chain workflows.",
+            "metavar": "WORKFLOW",
+        },
+    },
+    "enhance_stage": {
+        "flags": ("--enhance-stage",),
+        "kwargs": {
+            "action": "append",
+            "help": "Add inline enhancement stage (format: 'name:prompt'). Can be used multiple times.",
+            "metavar": "STAGE",
+        },
+    },
+    "var": {
+        "flags": ("--var",),
+        "kwargs": {
+            "action": "append",
+            "help": "Override workflow variable (format: 'key=value'). Can be used multiple times.",
+            "metavar": "VAR",
+        },
+    },
+    "workflow_dry_run": {
+        "flags": ("--workflow-dry-run",),
+        "kwargs": {
+            "action": "store_true",
+            "help": "Preview workflow stages without executing (requires --enhance-workflow)",
+        },
+    },
 }
 
 # Merge RAG arguments from common.py into universal arguments