[codex] remove stale duplicate project cards

[Sean-Kenneth-Doherty]

Summary

• remove older duplicate Mattermost and Ansible project cards
• keep the current Mattermost and Ansible entries already present later in the list
• reduce repeated project cards in the rendered project list

Validation

• Mattermost source count is 1 via src/data/projects.js import
• Ansible source count is 1 via src/data/projects.js import
• git diff --check
• GITHUB_TOKEN=$(gh auth token) pnpm build
• generated dist/index.html renders one Mattermost card and one Ansible card before restoring generated files

Related to #501

[Sean-Kenneth-Doherty]

Validated locally on head 62bceb74a73b90b86ce23457431f9a2a350ce233 in an isolated worktree:

• imported src/data/projects.js and confirmed source counts: Mattermost: 1, Ansible: 1
• git diff --check origin/main...HEAD && git diff --check
• GITHUB_TOKEN=$(gh auth token) pnpm build
• checked generated dist/index.html before restoring generated files; the kept Mattermost and Ansible project links each render once

All passed. gh pr checks reports no hosted checks on this branch.