Fixes #7402 What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch, not the main branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

If adding a new feature, the PR's description includes:

• add GET /memories backed by Chroma listMemories service with pagination
• add GET /summaries backed by listSummaries service returning metadata & docs
• keep responses aligned with MemoryCoreMcpApi design to unblock search + admin work Other information: