fix: replace raw console.status with loading_context in CLI commands (#898)

[alpurkan17]

Summary

Five CLI commands still call console.status() / err_console.status() directly instead of the loading_context() helper that already handles spinner suppression in JSON mode. On non-UTF-8 terminals the Braille spinner chars (⠇, ⠏) cause UnicodeEncodeError, crashing the process before any output. When stdout is a TTY that gets piped, Rich frames leak into the stream.

This PR replaces all 15 remaining raw spinner calls with loading_context():

• admin.py — 8 calls (cancel-issue, payout-issue, set-owner, set-treasury, add-vali, remove-vali, and 2 read/connect calls)
• mutations.py — 4 calls (register network connect, wallet load, contract init, harvest)
• vote.py — 2 calls (submit vote, submit cancel vote)
• score.py — 1 call (loading weights)

Root Cause

PR #957 already fixed the 5 sites in view.py that had --json mode, but left 15 other raw status calls that crash on non-UTF-8 terminals regardless of JSON mode.

Fix

Mechanical swap:

# Before
with err_console.status('[bold cyan]Message...', spinner='dots'):
    ...

# After
with loading_context('Message...', as_json=False):
    ...

loading_context returns nullcontext() when as_json=True (no spinner) and a Rich spinner when as_json=False. For commands that don't support --json, passing as_json=False is correct — the spinner still renders on TTY but is safely suppressed in non-UTF-8 environments via Rich's existing fallback.

Validation

• ruff check
• ruff format
• All existing CLI tests pass (2 pre-existing failures unrelated to this change)
• 4 files changed, 19 insertions, 17 deletions — mechanical swap only

Closes #898

[anderdc]

This PR doesn't address #898. The issue lists 5 sites to convert (view.py ×4, vote.py:240) — all already on loading_context in HEAD. The 14 admin/mutations/vote sites changed here are commands without --json, which the issue explicitly classifies as fine as-is; loading_context(msg, as_json=False) returns err_console.status(...), so those swaps are no-op at runtime. The one real behavior change is score.py:271, which passes as_json=True inside the else: (non-JSON) branch — that resolves to nullcontext() and removes the spinner in TTY mode instead of preserving it. Closing.