Developer Experience Improvements: JSON output, table pagination, balance command

[charliebot87]

Following up on #30 with three specific improvements from real-world usage:

1. --json flag on proton action

Problem: Action output is pretty-printed and hard to parse in scripts. When automating transactions, you want clean JSON you can pipe to jq or Python.

Suggestion:

proton action eosio.token transfer '{...}' myaccount --json
# Returns raw JSON: { "transaction_id": "abc123...", ... }

2. Pagination support on proton table

Problem: Large tables (e.g. simplelaunch curves with 400+ tokens) hit the row limit with no easy way to page through results.

Suggestion: Add --next flag using the next_key cursor returned by get_table_rows:

proton table simplelaunch curves --limit 100
# Output includes: next_key: "123"

proton table simplelaunch curves --limit 100 --lowerBound 123
# Continues from where you left off

Or add --all flag that automatically pages through and returns all rows.

3. proton balance <account> shorthand

Problem: Checking an account's token balances requires knowing the right table query (proton table eosio.token accounts <account>), which isn't obvious to new developers.

Suggestion: First-class balance command using the Light API:

proton balance myaccount
# XPR: 1,234.5678
# XUSDC: 50.00

proton balance myaccount --symbol XPR
# 1,234.5678 XPR

proton balance myaccount --json
# [{ "symbol": "XPR", "amount": "1234.5678", "contract": "eosio.token" }]

Could use the Light API (https://lightapi.eosamsterdam.net/api) for efficiency rather than direct table queries.

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Happy to contribute PRs for any of these if there's interest.