feat: Unified create command + consolidated enhancement flags

This commit includes two major improvements:

## 1. Unified Create Command (v3.0.0 feature)
- Auto-detects source type (web, GitHub, local, PDF, config)
- Three-tier argument organization (universal, source-specific, advanced)
- Routes to existing scrapers (100% backward compatible)
- Progressive disclosure: 15 universal flags in default help

**New files:**
- src/skill_seekers/cli/source_detector.py - Auto-detection logic
- src/skill_seekers/cli/arguments/create.py - Argument definitions
- src/skill_seekers/cli/create_command.py - Main orchestrator
- src/skill_seekers/cli/parsers/create_parser.py - Parser integration

**Tests:**
- tests/test_source_detector.py (35 tests)
- tests/test_create_arguments.py (30 tests)
- tests/test_create_integration_basic.py (10 tests)

## 2. Enhanced Flag Consolidation (Phase 1)
- Consolidated 3 flags (--enhance, --enhance-local, --enhance-level) → 1 flag
- --enhance-level 0-3 with auto-detection of API vs LOCAL mode
- Default: --enhance-level 2 (balanced enhancement)

**Modified files:**
- arguments/{common,create,scrape,github,analyze}.py - Added enhance_level
- {doc_scraper,github_scraper,config_extractor,main}.py - Updated logic
- create_command.py - Uses consolidated flag

**Auto-detection:**
- If ANTHROPIC_API_KEY set → API mode
- Else → LOCAL mode (Claude Code)

## 3. PresetManager Bug Fix
- Fixed module naming conflict (presets.py vs presets/ directory)
- Moved presets.py → presets/manager.py
- Updated __init__.py exports

**Test Results:**
- All 160+ tests passing
- Zero regressions
- 100% backward compatible

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

src/skill_seekers/cli/arguments/pdf.py

@@ -0,0 +1,61 @@
+"""PDF command argument definitions.
+
+This module defines ALL arguments for the pdf command in ONE place.
+Both pdf_scraper.py (standalone) and parsers/pdf_parser.py (unified CLI)
+import and use these definitions.
+"""
+
+import argparse
+from typing import Dict, Any
+
+
+PDF_ARGUMENTS: Dict[str, Dict[str, Any]] = {
+    "config": {
+        "flags": ("--config",),
+        "kwargs": {
+            "type": str,
+            "help": "PDF config JSON file",
+            "metavar": "FILE",
+        },
+    },
+    "pdf": {
+        "flags": ("--pdf",),
+        "kwargs": {
+            "type": str,
+            "help": "Direct PDF file path",
+            "metavar": "PATH",
+        },
+    },
+    "name": {
+        "flags": ("--name",),
+        "kwargs": {
+            "type": str,
+            "help": "Skill name (used with --pdf)",
+            "metavar": "NAME",
+        },
+    },
+    "description": {
+        "flags": ("--description",),
+        "kwargs": {
+            "type": str,
+            "help": "Skill description",
+            "metavar": "TEXT",
+        },
+    },
+    "from_json": {
+        "flags": ("--from-json",),
+        "kwargs": {
+            "type": str,
+            "help": "Build skill from extracted JSON",
+            "metavar": "FILE",
+        },
+    },
+}
+
+
+def add_pdf_arguments(parser: argparse.ArgumentParser) -> None:
+    """Add all pdf command arguments to a parser."""
+    for arg_name, arg_def in PDF_ARGUMENTS.items():
+        flags = arg_def["flags"]
+        kwargs = arg_def["kwargs"]
+        parser.add_argument(*flags, **kwargs)