feat: add versioning infrastructure and release script

- Fix version mismatch: __init__.py had 'v1.0.0', pyproject.toml had '0.1.0'
  Now both use '0.1.0' (no v prefix — added in display code only)
- Add __release_date__ for CalVer date tracking alongside SemVer version
- Fix double-v bug in cmd_version (was printing 'vv1.0.0')
- Update banner title to show 'Hermes Agent v0.1.0 (2026.3.12)' format
- Update cli.py banner to match new format
- Add scripts/release.py: full release automation tool
  - Generates categorized changelogs from git history
  - Maps git authors to GitHub @mentions (70+ contributors)
  - Supports dry-run preview and --publish mode
  - Creates annotated CalVer git tags + GitHub Releases
  - Bumps semver in source files automatically
  - Usage: python scripts/release.py --bump minor --publish
- Add .release_notes.md to .gitignore

Versioning scheme: CalVer tags (v2026.3.12) + SemVer display (v0.1.0)

cli.py

@@ -416,7 +416,7 @@ from model_tools import get_tool_definitions, get_toolset_for_tool
 # Extracted CLI modules (Phase 3)
 from hermes_cli.banner import (
     cprint as _cprint, _GOLD, _BOLD, _DIM, _RST,
-    VERSION, HERMES_AGENT_LOGO, HERMES_CADUCEUS, COMPACT_BANNER,
+    VERSION, RELEASE_DATE, HERMES_AGENT_LOGO, HERMES_CADUCEUS, COMPACT_BANNER,
     get_available_skills as _get_available_skills,
     build_welcome_banner,
 )
@@ -993,7 +993,7 @@ def build_welcome_banner(console: Console, model: str, cwd: str, tools: List[dic
     # Wrap in a panel with the title
     outer_panel = Panel(
         layout_table,
-        title=f"[bold {_title_c}]{_agent_name} {VERSION}[/]",
+        title=f"[bold {_title_c}]{_agent_name} v{VERSION} ({RELEASE_DATE})[/]",
         border_style=_border_c,
         padding=(0, 2),
     )