fix(quota): correct current_interval_usage_count to hold actual usage

[xandersbell]

Summary

API fields current_interval_usage_count and current_weekly_usage_count actually hold remaining quota (not usage as the name implies). This caused mmx quota show --output json to expose semantically incorrect data.

Root cause

The upstream API itself returns remaining quota in fields named current_interval_usage_count / current_weekly_usage_count. The ideal fix would be upstream renaming the fields to match their actual semantics.

Why this approach

We evaluated two options:

1. Add new semantically correct fields (e.g. current_interval_remaining_count): Cleaner semantics but changes the JSON schema, breaking any downstream consumers that depend on exact field names.
2. Fix existing field values in-place: No schema change, no new fields — only corrects the values to match what the field names imply. Respects the original API contract.

We chose option 2.

Changes (no schema change — only fix field values)

src/commands/quota/show.ts

• --output json: current_interval_usage_count now holds actual usage (total - original_value). Same for weekly fields.
• --quiet: Uses fixed values for correct used/remaining display.
• Table rendering already correct — no changes needed.

test/commands/quota/show.test.ts: 5 test cases covering all output modes.

Closes #68

[xandersbell]

Commit history note

Initial version of this PR introduced new fields (current_interval_remaining_count, current_weekly_remaining_count) to carry the semantically correct values alongside the original fields.

After discussion we reverted to fixing only the existing field values in-place — no new fields, no schema change. This approach respects the original API contract and avoids breaking any downstream consumers that may depend on the exact field names.

[xandersbell]

Note: The root cause is upstream — the API itself returns remaining quota in fields named current_interval_usage_count / current_weekly_usage_count. This CLI fix is a compensating correction since the API layer cannot be modified. The ideal fix would be upstream renaming the fields to match their actual semantics.