Fix double slash in Micropub URL construction

- Remove leading slash when constructing URLs with SITE_URL
- SITE_URL already includes trailing slash per IndieAuth spec
- Fixes malformed Location header in Micropub responses
- Fixes malformed URLs in Microformats2 query responses

Changes:
- starpunk/micropub.py line 312: f"{site_url}notes/{note.slug}"
- starpunk/micropub.py line 383: f"{site_url}notes/{note.slug}"
- Added comments explaining SITE_URL trailing slash convention
- Updated version to 1.0.1 in starpunk/__init__.py
- Updated CHANGELOG.md with v1.0.1 release notes

Fixes double slash issue reported after v1.0.0 release.

Per ADR-039 and docs/releases/v1.0.1-hotfix-plan.md

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

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

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.0.1] - 2025-11-25
+
+### Fixed
+- Micropub Location header no longer contains double slash in URL
+- Microformats2 query response URLs no longer contain double slash
+
+### Technical Details
+Fixed URL construction in micropub.py to account for SITE_URL having a trailing slash (required for IndieAuth spec compliance). Changed from `f"{site_url}/notes/{slug}"` to `f"{site_url}notes/{slug}"` at two locations (lines 312 and 383). Added comments explaining the trailing slash convention.
+
 ## [1.0.0] - 2025-11-24
 
 ### Released