chore: bump version to 1.0.0

Mark Gondulf as production-ready v1.0.0 release.

All W3C IndieAuth specification requirements met:
- Client identifier validation (Section 3)
- Discovery endpoint (Section 4)
- Authorization flows (Section 5)
- Token endpoint - issuance and verification (Section 6-7)
- Domain verification via DNS
- Email-based authentication
- 533 tests passing, 90.51% coverage

Successfully tested with real-world IndieAuth clients.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "gondulf"
-version = "1.0.0-rc.1"
+version = "1.0.0"
 description = "A self-hosted IndieAuth server implementation"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -10,7 +10,7 @@ authors = [
 ]
 keywords = ["indieauth", "oauth2", "authentication", "self-hosted"]
 classifiers = [
-    "Development Status :: 3 - Alpha",
+    "Development Status :: 5 - Production/Stable",
     "Intended Audience :: Developers",
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python :: 3",