/budget command surface only half-supports the 'profile' scope (set + status missing)

[nujovich]

Summary

The profile budget scope is enforced and configurable via budget.yaml, but the /budget command surface only half-exposes it: /budget forecast accepts profile, while /budget set rejects it and the /budget status block never lists per-profile budgets. Today the only way to create or see a per-profile budget through the plugin is hand-editing budget.yaml.

Current behavior

• /budget set profile <id> … → rejected with Unknown scope 'profile' (budget.py:637-638). The usage string lists only <global|cron_job|sender> (budget.py:702-703), and there is no per_profile write branch (budget.py:653-658).
• /budget status omits profiles — it enumerates global, cron jobs and senders, but there is no profile section and no db.list_profile_ids() helper (budget.py:532-549).
• /budget forecast <window> profile <id> → accepted (budget.py:695).
• Enforcement works: evaluate_run checks the profile scope (budget.py:339-343) and _resolve_limits reads budgets.per_profile (budget.py:239-242).
• Manual config works: budget.example.yaml documents the per_profile: block.

Impact

forecast advertises a profile scope that set cannot create, which is inconsistent. Anyone acting on the "per-profile budgets" capability naturally tries /budget set profile <name> daily 10 and hits Unknown scope, with no in-command way to configure or inspect the limit.

Proposed fix

1. _set_budget: accept profile and write to budgets.per_profile.default[<window>_usd], mirroring the cron_job/sender pattern. Update the scope guard and the Usage: string.
2. _status_block: add a "Profiles:" section, backed by a new db.list_profile_ids(since_iso) helper (mirroring list_cron_job_ids/list_sender_ids), excluding NULL profiles.
3. Tests for both paths, plus an ONBOARDING/README refresh of the /budget command docs.

Note: as with cron_job/sender, set would only write the default bucket; per-id overrides stay YAML-only (out of scope here). No schema change is needed — runs.profile already exists (v12).