Stop bypassing the knowpro.interfaces aggregator

[Bernhard Merkle (bmerkle)]

Summary

interfaces.py explicitly re-exports interfaces_core/interfaces_indexes/interfaces_search/interfaces_serialization/interfaces_storage via __all__ (exempted from AGENTS.md's "no re-export" rule by its own exception clause), but 4 files partially imported some symbols through it and others directly from the defining submodule:

• conversation_base.py: TextLocation (from interfaces_core)
• add_messages.py: IKnowledgeExtractor, IMessage, MessageOrdinal, TextLocation (from interfaces_core)
• storage/sqlite/provider.py: ChunkFailure (from interfaces_storage)
• podcast_ingest.py: AddMessagesResult (from interfaces_core)

Investigated and ruled out both plausible justifications (details in #298):

• Not a circular-import workaround — none of the interfaces_*.py submodules import anything from these 4 files.
• Not a missing-export issue — every bypassed symbol is confirmed present in the relevant submodule's __all__.

Git history shows the bypass lines were added months after the aggregator existed (2025-12-31), across unrelated feature commits (streaming API, batching/pipeline overlap) with no import-style rationale — incidental, not deliberate.

Merges each bypassed import into the existing (or a new) from .interfaces import (...) block.

Found via a whole-project import-style scan, tracked in #298.

Test plan

• make (format, check on 3.12/3.14, test, build) — 0 pyright errors, 737 passed / 12 skipped, wheel builds

[Copilot]

Pull request overview

This PR standardizes import style by routing several knowpro interface symbol imports through the knowpro.interfaces aggregator module, eliminating “bypass” imports that reached directly into interfaces_core / interfaces_storage.

Changes:

• Consolidate ChunkFailure, ConversationMetadata, and STATUS_INGESTED imports in the SQLite provider to come from knowpro.interfaces.
• Consolidate AddMessagesResult and Datetime imports in podcast ingest to come from knowpro.interfaces.
• Consolidate TextLocation and other interface symbols in knowpro core modules (conversation_base.py, add_messages.py) to come from knowpro.interfaces.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/typeagent/storage/sqlite/provider.py	Merges ChunkFailure into the existing knowpro.interfaces import.
src/typeagent/podcasts/podcast_ingest.py	Imports AddMessagesResult via the knowpro.interfaces aggregator instead of interfaces_core.
src/typeagent/knowpro/conversation_base.py	Removes direct interfaces_core import of TextLocation, using the aggregator import block instead.
src/typeagent/knowpro/add_messages.py	Consolidates several interface-symbol imports into a single from .interfaces import (...) block.

[Bernhard Merkle (bmerkle)]

robgruen would you mind taking a look at this one when you get a chance? Thanks!