collab: Add granular tokens per minute columns to models table (#28090)

This PR adds new granular tokens per minute columns to the `models`
table in preparation for more fine-grained rate limits.

The following columns have been added:

- `max_input_tokens_per_minute`
- `max_output_tokens_per_minute`

These mirror the "Maximum input tokens per minute (ITPM)" and "Maximum
output tokens per minute (OTPM)" [rate limits from
Anthropic](https://docs.anthropic.com/en/api/rate-limits#rate-limits).

Release Notes:

- N/A

crates/collab/migrations_llm/20250404141155_add_granular_token_limits_to_models.sql

@@ -0,0 +1,3 @@
+alter table models
+    add column max_input_tokens_per_minute bigint not null default 0,
+    add column max_output_tokens_per_minute bigint not null default 0;

crates/collab/src/llm/db/tables/model.rs

@@ -12,6 +12,8 @@ pub struct Model {
     pub name: String,
     pub max_requests_per_minute: i64,
     pub max_tokens_per_minute: i64,
+    pub max_input_tokens_per_minute: i64,
+    pub max_output_tokens_per_minute: i64,
     pub max_tokens_per_day: i64,
     pub price_per_million_input_tokens: i32,
     pub price_per_million_cache_creation_input_tokens: i32,