feat(captain): expand assistant description limit (#14985)

# Pull Request Template

## Description

Increases description for Captain.

Why?
We are planning to include business context in description and 255 char
limit on the column and 200 char limit on the UI are very limiting to
get proper context.

## Type of change

Improvement to accommodate business context

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration.
locally

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

db/migrate/20260710000000_change_captain_assistant_description_to_text.rb

@@ -0,0 +1,9 @@
+class ChangeCaptainAssistantDescriptionToText < ActiveRecord::Migration[7.0]
+  def up
+    change_column :captain_assistants, :description, :text
+  end
+
+  def down
+    change_column :captain_assistants, :description, :string
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2026_07_06_215758) do
+ActiveRecord::Schema[7.1].define(version: 2026_07_10_000000) do
   # These extensions should be enabled to support this database
   enable_extension "pg_stat_statements"
   enable_extension "pg_trgm"
@@ -343,7 +343,7 @@ ActiveRecord::Schema[7.1].define(version: 2026_07_06_215758) do
   create_table "captain_assistants", force: :cascade do |t|
     t.string "name", null: false
     t.bigint "account_id", null: false
-    t.string "description"
+    t.text "description"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.jsonb "config", default: {}, null: false