limits: a daily token quota for the account the stack uses, and bus schema 3h to 3i (row 126, #1620)

The business file can name the account claude-code launches use,
`launch.account` = {name, credential}. `name` is an identifier and
`credential` names one login set's environment variables, never a value.
`launch.limits.tokens.daily.<account>` = {limit, since, reset, timeZone}
sets a daily quota for that account. A daily key that isn't the account's
name refuses the business read.

The new plug-in limit-check/daily-quota (interface 2, pure) starts a day at
the first instant at or after `reset` on that local date in `timeZone`. Across
DST that makes a 23- or 25-hour day, and a reset in a skipped hour starts at
the gap's end. It counts the account's known records of all four kinds since
the later of the day start and `since`, and counts unknown turns apart.

The launcher refuses account-credential-missing, account-credential-ambiguous
and account-is-credential (an account name equal to a session credential's
value). Messages name variables, never values. The account rides mayLaunch,
bindLaunch, the usage records, mustStop and the launch record. A pi launch
has no account, records NULL, and no daily quota covers it. `mosaic limits`
and the Console's Settings show one fixed line when a daily row shows:
"Daily quotas count only this stack's own use of the account, not its use
anywhere else."

Bus schema 3h to 3i: 3h reserved usage_records.account as
CHECK (account IS NULL). The new step 3h-3i.sql rebuilds the table in one
transaction, keeping every row's seq and the sqlite_sequence value, and
recreates the three append-only triggers byte-identical. sqlite_master
differs from 3h only in the account line. A 3h engine refuses a 3i store.
packages/bus/tests/account-migration.test.mjs covers all three, with a
step that fails partway and leaves 3h intact. 3i goes live only through
`stack-release.sh activate ... --migrate` with Jason present; the activate
path takes the pre-migrate backup, and the way back is restoring it
(agents/dewey/work/queue-126/MIGRATION.md). Mos's go mos-0835, six
conditions, each with its check in the packet's BUILD.md.

The public/ change in bus.js (the daily line under the token-limit table)
carries Mos's decision 123 go mos-0833 on the +/- digest 03e6d9da...ba78,
unchanged at landing.

Owner Dewey, brief docs/plans/2026-10-14_prd-1.2-build.md, "Daily quota for
the credential the stack uses today". Review round 2 rebases the round 4
build onto 1df04f52f (row 167). Reviewer: Filbert approve 29068 on review
round 1 (manifest d18314f7...8e65).

Nothing live.