fix(ci): more changes to fix failing CI (#415)

Fixes from maphew including:
- Remove test for deleted isPathWithinDir function
- Add gosec nolint directives for safe file operations
- Add rm -rf .beads before init in CI workflow
- Simplify panic handling and file operations

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

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

.github/workflows/ci.yml

@@ -101,6 +101,7 @@ jobs:
         run: |
           export BEADS_DB="$PWD/.ci-beads/beads.db"
           mkdir -p "$(dirname "$BEADS_DB")"
+          rm -rf .beads
           nix run .#default -- --db "$BEADS_DB" init --quiet --prefix ci
           nix run .#default -- --db "$BEADS_DB" > help.txt
       - name: Verify help text