fix(cli): honor configured wallet/hotkey for vote/admin/harvest signing

[statxc]

Summary

gitt config set wallet/hotkey writes canonical keys to ~/.gittensor/config.json,
and gitt issues register already honors them when wallet flags are omitted. The
other signed issue-contract write commands did not — gitt vote *, gitt admin *,
and gitt harvest passed their raw Click defaults straight into bt.Wallet(...), so
a user with a configured wallet/hotkey could silently sign with the wrong key (or fail
because the command's fallback wallet doesn't exist) for irreversible on-chain actions.

This is the wallet/hotkey member of the CLI config-priority family already fixed for
adjacent keys in #1035, #1200, and #1364.

Closes #1424

Affected commands

Shared _make_contract_client(...) path: gitt vote solution, gitt vote cancel,
gitt admin cancel-issue, gitt admin payout-issue, gitt admin set-owner,
gitt admin set-treasury, gitt admin add-vali, gitt admin remove-vali.

Inline wallet construction: gitt harvest.

Fix

Adds a shared resolve_wallet_config(...) helper applying the documented priority:

1. Explicit --wallet-name / --wallet-hotkey CLI flags win.
2. ~/.gittensor/config.json wallet / hotkey when the flag is omitted.
3. The command's own Click default otherwise.

Whether a flag was supplied is detected via Click's ParameterSource, not a
!= "default" comparison. This matters because gitt harvest carries a non-"default"
fallback (validator), so a value comparison would mistake that fallback for an explicit
value and never consult config — and only a parameter-source check lets an explicit
--wallet default win over config. A no-Click-context fallback (value comparison) keeps
the helper usable in direct unit calls.

Wired into:

• _make_contract_client(...) — the shared vote/admin path (default/default fallback).
• gitt harvest — inline construction (validator/default fallback); the displayed
  Wallet: line now reflects the resolved key.

gitt issues register is intentionally left unchanged — it already honors config and has
special //Alice local-dev handling.

Tests

New TestWalletConfigResolution covering every scenario:

• vote/admin without flags use configured wallet / hotkey
• vote/admin explicit flags win
• explicit --wallet default --hotkey default still beats config
• vote/admin without config preserve default/default
• harvest without flags uses configured wallet / hotkey
• harvest without config preserves validator/default
• harvest explicit flags win
• direct (no-Click-context) fallback path

Verification

• uv run pytest tests/ → 918 passed (+8 new)
• ruff lint + format, pyright (0 errors), vulture: all clean
• Verified end-to-end against a real config.json file-read path

[anderdc]

remove the tests, it's a simple fix

[statxc]

Hi @anderdc how are you? I've removed all test. Thanks for the review.