Fix Codex TOML parsing dropping multi-line/trailing-comma args arrays (silent version wipe on re-setup)

[wallidsaydi-creator]

Follow-up to #3060 (thanks @fahreddinozcan for the quick ack). Opening this PR so the fix is reviewable directly — no pressure on timing.

What it fixes

readTomlServerEntry in packages/cli/src/setup/mcp-writer.ts parses Codex config.toml server entries with per-line JSON.parse, which silently drops args when:

1. The array is multi-line — what taplo/Prettier/cargo-fmt produce once a line exceeds print width (any real API key makes this likely).
2. The array has a trailing comma — valid TOML, invalid JSON.

Downstream, isStdioContext7Entry then fails, resolveEntryToWrite falls back to a fresh canonical entry, and a re-setup that was only meant to rotate the API key silently wipes the user's pinned @upstash/context7-mcp@<version> to a floating version. Full repro chain in #3060.

The change

• String-aware bracket balancing to join multi-line arrays before parsing.
• String-aware trailing-comma strip (commas inside string literals are untouched).

Verification

• Repro cases from CLI setup silently drops pinned @upstash/context7-mcp version on re-setup when Codex config.toml arrays are multi-line or have trailing commas (readTomlServerEntry drops args) #3060: 3/3 pass with the patch, fail on unpatched main (git-stash control).
• Edge cases: multi-line array with embedded commas in strings; trailing-comma single-line array — both parse correctly.
• Full CLI suite: 254/254 passing; tsc --noEmit clean.