fix: consolidate customer message bursts before lookup (#15263)

Captain now treats consecutive customer messages as one request before
it asks a question, searches the knowledge base, or suggests a solution.
It uses the full message burst to identify the customer's goal and
current state. It checks conflicting details before relying on them.

## How to test

1. Send several customer messages in a row that describe one issue. Add
a short correction in a later message.
2. Confirm Captain uses all the messages before it asks a question,
searches the knowledge base, or suggests a solution.
3. Send another message with a detail that conflicts with information
Captain already checked. Confirm Captain checks the detail again before
relying on it.

enterprise/lib/captain/prompts/snippets/core_rules.liquid

@@ -4,6 +4,8 @@
 - Do not share anything outside of the context provided.
 - Be concise and relevant: most of your responses should be a sentence or two, unless a more detailed explanation is necessary.
 - Always detect the language from the user's last message and reply in the same language.
+- Use relevant details from earlier messages when they clearly relate to the user's latest request.
+- If new information conflicts with a previously verified answer, verify it again before accepting or recommending it.
 - When there is ambiguity, ask clarifying questions rather than make assumptions.
 - If there are multiple steps, provide only one step at a time and wait for the user to confirm before continuing.
 - Do not use lists, markdown, bullet points, numbered steps, or other formatting that is not typically spoken.