chore(deps): bump mermaid to 12 and tauri plugins

[mattenarle10]

Rolls up the open dependabot PRs into one change and re-syncs bun.lock (it had drifted, so bun install --frozen-lockfile failed on main).

• mermaid 11.17.2 → 12.0.0 (supersedes chore(deps): bump mermaid from 11.17.2 to 12.0.0 #151) — new default look (ELK layout, neo appearance); needs Safari 17.4+ webview
• tauri-plugin-updater 2.10.1 → 2.12.0 (supersedes chore(deps): bump tauri-plugin-updater from 2.10.1 to 2.11.0 in /src-tauri #145)
• tauri-plugin-fs 2.5.1 → 2.5.2 (supersedes chore(deps): bump tauri-plugin-fs from 2.5.1 to 2.5.2 in /src-tauri #146)
• tauri-plugin-single-instance 2.4.3 → 2.4.5 (supersedes chore(deps): bump tauri-plugin-single-instance from 2.4.3 to 2.4.4 in /src-tauri #147)
• tauri-plugin-dialog 2.7.2 → 2.7.3 (supersedes chore(deps): bump tauri-plugin-dialog from 2.7.2 to 2.7.3 in /src-tauri #148)
• tauri-plugin-opener 2.5.4 → 2.5.5 (supersedes chore(deps): bump tauri-plugin-opener from 2.5.4 to 2.5.5 in /src-tauri #149)

Verified locally: bun install --frozen-lockfile, bun test (84 pass), bun run build, cargo check, cargo fmt --check.