Privacy-first: remove 'https:' from img-src CSP directive to prevent
IP leaks via external avatar URLs (Google/Gravatar). AccountCard now
shows user initials instead of loading a remote image.
Also remove .keys-temp/ from .gitignore (not relevant to this PR).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>