docs: add wiki pages for all audiences, fix .old.yml leak

9 new wiki pages: getting-started, faq, troubleshooting,
advanced-usage, verification-modes, adding-a-platform,
adding-a-scraper, testing-guide, release-process.

Updated architecture.md with mermaid diagrams, tools.md with
full pipeline and target/exporter sections, profiling.md with
missing fields, index.md with glossary and nav links.

Expanded CONTRIBUTING.md from stub to full contributor guide.

Filter .old.yml from load_emulator_profiles, generate_db alias
collection, and generate_readme counts. Fix BizHawk sha1 mode
in tools.md, fix RetroPie path, fix export_truth.py typos.

scripts/generate_readme.py

@@ -91,6 +91,7 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
 
     emulator_count = sum(
         1 for f in Path("emulators").glob("*.yml")
+        if not f.name.endswith(".old.yml")
     ) if Path("emulators").exists() else 0
 
     # Count systems from emulator profiles
@@ -100,6 +101,8 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
         try:
             import yaml
             for f in emu_dir.glob("*.yml"):
+                if f.name.endswith(".old.yml"):
+                    continue
                 with open(f) as fh:
                     p = yaml.safe_load(fh) or {}
                 system_ids.update(p.get("systems", []))