refactor: review & simplify nsc/cli/handlers.py

[thomaschristory]

Scope

nsc/cli/handlers.py (660 lines) — the largest file in the codebase.

Goal

Code review + simplify pass:

• Identify dead branches or over-defensive conditionals
• Extract any logic that belongs in a lower layer (model/, output/)
• Reduce cyclomatic complexity where possible
• Ensure all type annotations are tight (mypy --strict clean, no Any escapes)
• Remove or tighten comments that describe what rather than why

Files

• nsc/cli/handlers.py
• Related tests: tests/cli/

[thomaschristory]

Claiming #47. Branch: refactor/auth-simplify. Reviewing nsc/auth/login.py, rotate.py, probe.py.

[thomaschristory]

Done. PR: #67

[thomaschristory]

No changes needed — nsc/auth/login.py, rotate.py, probe.py were already clean after Wave 1. PR #67 closed (agent went off-scope to cli/handlers.py).

[thomaschristory]

Addressed by PR #68 (refactor(cli): simplify cli package) — nsc/cli/handlers.py simplified as part of the Wave 2 cli pass. All tests pass.