fix(ai): assistant sql row cap - #51608

## Problem

attempt to [fix this
ticket](https://supabase.frontapp.com/inboxes/teams/folders/27650590/unassigned/116845868830):
when the studio ai assistant runs a query with previously set database
opt-in, `execute_sql` returns every row while the query cell's footer
says "Limit 100 rows" causing in case of large amount of returned rows
browser to freeze

+ the chat fails with "Sorry, I'm having trouble responding right now"
until the user clears it

## Solution

- `execute_sql` now keeps the first 100 rows using the cell's existing
`DEFAULT_CELL_ROW_LIMIT`
- uses in history sanitizer the same `toModelRows` helper
- chats saved before this change have no `totalRows` so the helper falls
back to `rows.length` and cuts them to 100 too

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## Review instructions

1. In a test project, run this in the SQL editor:
   ```sql
create table "emailSubscriber" (id bigint generated always as identity
primary key, email text);
create table "stripeCustomer" (id bigint generated always as identity
primary key, email text);
insert into "emailSubscriber" (email) select md5(g::text) ||
'@example.com' from generate_series(1, 50000) g;
insert into "stripeCustomer" (email) select md5(g::text) ||
'@example.com' from generate_series(1, 1000) g;
2. on the live dashboard, open the assistant in a new chat and send "i
want all the emails in emailSubscriber where the email is not in the
stripeCustomer table"
3. in the opt in requested settings choose "Schema, Logs & Database
Data"
4. then click run query, the cell should show 100 rows (vs 50000 rows in
prod)

## Checklist

Check all before review:

- [x] I have read
[CONTRIBUTING.md](https://github.com/supabase/supabase/blob/master/CONTRIBUTING.md)
- [x] If I wrote a new docs topic or edited an existing topic, I used
the `/write-the-docs` or `/edit-the-docs` skill, which applies the docs
[style
guide](https://github.com/supabase/supabase/tree/master/apps/docs/style-guide)

---------

Co-authored-by: Joshen Lim <joshenlimek@gmail.com>

The previous commit was built on an older base and overwrote changes from
#51608: it removed the execute_sql row cap and declared aiOptInLevel twice
in the assistant context. #51608 already tells the model the current opt-in
level, so this restores those files and keeps only the approval and card
changes for already-granted opt-in requests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>