FEAT normalize messages before sending

[hannahwestra25]

Description

Utilize the Normalization Pipeline in the Target Send Path

PR 4 of the TargetConfiguration roadmap

Problem

The TargetConfiguration.normalize_async pipeline (system-squash, history-squash, etc.) was fully built in this PR but never called. Every target independently fetched conversation history, appended the current message, and sent it to the API — some with ad-hoc normalization (AzureMLChatTarget), most with none at all. This meant the centralized normalization pipeline was dead code, and normalization behavior was inconsistent across targets.

Solution

Wire the normalization pipeline into the send path so that every prompt passes through configuration.normalize_async() before reaching the target's API call. This is done by making send_prompt_async a concrete template method on PromptTarget that validates, fetches conversation from memory, runs the normalization pipeline, and delegates to a new _send_prompt_target_async abstract method for wire-format-specific logic.

Changes

• PromptTarget.send_prompt_async: Now a concrete method that calls self.configuration.normalize_async(messages=...) and passes the result to _send_prompt_target_async
• All 20 target subclasses: Renamed send_prompt_async → _send_prompt_target_async, removed duplicated validation/memory-fetch boilerplate, now receive the pre-normalized conversation directly
• AzureMLChatTarget: message_normalizer parameter deprecated with auto-translation to TargetConfiguration(policy={SYSTEM_PROMPT: ADAPT}); will be removed in v0.14.0

Breaking Changes

• Target authors must override _send_prompt_target_async instead of send_prompt_async

Tests and Documentation

• Tests: Updated all mocks/stubs to new signature; added test_normalize_async_integration.py (395 lines) covering normalize-is-called, normalized-conversation-is-used, memory-not-mutated, and legacy deprecation paths

wip: running integration tests

[romanlutz]

Don't we need tests for this?

Nvm didn't render first time I looked!

[rlundeen2]

Approved, but have one suggestion for insidious bug; not a blocker but worth thinking through