feat: add gitt miner status command

[eureka0928]

Description

Miners currently have no way to check their eligibility gate progress from the CLI. They must wait for validator scoring to find out if they meet the merged PR count and credibility thresholds.

Proposal

Add gitt miner status command that:

• Validates the miner's GitHub PAT
• Resolves wallet/hotkey UID on the network
• Fetches PRs across incentivized repos using the existing GraphQL pipeline (load_miners_prs)
• Calculates credibility locally (calculate_credibility)
• Displays eligibility status (merged PR count, credibility, pass/fail)

Lightweight approach

No token scoring / tree-sitter / file fetching — that's validator-side only. Shows LIKELY ELIGIBLE with a caveat since token_score >= 5 can't be verified without the full pipeline.

Options

• --detail — per-PR breakdown table
• --json-output — structured JSON for scripting/automation
• --wallet, --hotkey, --network, --pat — standard miner options

Example output

Miner Status
UID: 42  |  GitHub: @alice  |  Network: wss://test.finney.opentensor.ai

Eligibility Gate
  Merged PRs:    7/5  pass
  Credibility:   0.88/0.75  pass  (7M/1C, 1 mulligan)
  Status:        LIKELY ELIGIBLE
  Note: Final eligibility depends on token scoring by validators

Lookback Window (35 days)
  Merged: 7  |  Open: 2  |  Closed: 2
  Unique repos: 4