docs: v0.49.1 release notes — Docker docs + mobile Profiles button

- CHANGELOG: entries for #291 (Docker docs) and #265 (mobile Profiles button)
- ROADMAP: sprint table row + header date/count updated to v0.49.1/700
- TESTING.md: test count 700
- SPRINTS.md: version v0.49.1 + test count 700
- static/index.html: version bumped to v0.49.1

Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>

SPRINTS.md

@@ -1164,7 +1164,7 @@ New test cases in `tests/test_sprint26.py`:
 ---
 
 *Last updated: April 12, 2026*
-*Current version: v0.49.0 | 697 tests*
+*Current version: v0.49.1 | 700 tests*
 *Next sprint: Sprint 24 (Web Polish + Bug Fix Pass)*
 *Horizon sprint: Sprint 25 (macOS Desktop Application)*
 *Docs sweep policy: update markdown proactively during PR reviews and after significant releases*