clarity playground components

[ryanwaits]

feat: provide configurable playground options (e.g., change network epoch, RPC URL, gas limits).

• Ability to view & interact with previously deployed contracts
• Configurable playground options (epoch, RPC URL, gas limits, …)
• Contract-validation checks before deploy/call
• Dual-tab playground: Clarity ↔ Stacks.js
• Auto-generate Stacks.js code from a contract call configured in the Clarity tab
• Re-use UI components & logic for stored snippets (dropdown of example snippets)