Add run sharing + run credit cost lookup + bump version (0.3.14)

[aliroberts]

Summary

• Run sharing (opt-in): Adds a new weco share <run_id> command that creates a public share link for an existing run (requires the user to enable CLI sharing in the dashboard).
• Run cost visibility: Adds weco credits cost <run_id> to fetch and display credits spent for a run (including per-step breakdown + total).

Changes

• New command: weco share <run_id>

  • Calls POST /runs/{run_id}/share and expects {"share_id": "..."}.
  • Prints a dashboard URL in the form: {DASHBOARD_URL}/share/{share_id}.
  • Supports --output rich|plain (default rich) so agents/scripts can consume a clean URL (plain).
  • Implementation:
    • weco/api.py: create_share_link(...)
    • weco/share.py: handle_share_command(...)
    • weco/cli.py: wires up the share subcommand

• New command: weco credits cost <run_id>

  • Calls GET /billing/run/{run_id}/cost.
  • Renders a Rich table showing:
    • step number
    • node id
    • credits spent per step
    • total credits spent
  • Includes basic HTTP error handling (401/403/404 + fallback).
  • Implementation:
    • weco/cli.py: adds credits cost subcommand under weco credits
    • weco/credits.py: check_run_cost(...) and dispatch in handle_credits_command(...)

Notes / UX

• Sharing is explicitly opt-in: CLI sharing requires enabling in dashboard settings (guardrail to prevent accidental public sharing).
• Automation-friendly output: weco share ... --output plain prints only the share URL for easy piping into agents/tools.