rc.7: retire in-process AI and generated knowledgebase; preserve Netclaw ticket chat and MCP

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Owner-directed scope

Remove the legacy AI/knowledgebase proof of concept from RatelDesk: ticket-closure knowledge generation, embeddings and pgvector storage, knowledgebase API/UI/admin controls, in-process model/provider integrations and Microsoft AI/vector abstractions used only by that stack.

Preserve the working Netclaw SignalR ticket assistant and all supported MCP HTTP/stdio tooling, authorization, attachments and normal ticket workflows. Do not add a Memorizer integration in this change; external knowledge integration is a future project.

Acceptance

• Trace incident/request/change closure and background jobs before removal; document what existed.
• Ordinary PostgreSQL and SQLite initialize without vector extensions or model-provider credentials. Review pg_trgm separately so non-AI search remains correct.
• Upgrade previously migrated databases safely; account for queued/recurring legacy jobs and provider migration history without dropping unrelated objects or using extension CASCADE.
• Remove abandoned APIs, navigation, configuration, DI and package references rather than merely hiding/disabling them.
• Verify preserved Netclaw SignalR assistant and MCP contracts with regressions, and build/test both providers.
• Set version to 0.1.0-rc.7 and open a fix-branch PR to main. Do not merge, tag, release or deploy.

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Implemented in draft PR #49: #49

Completed:

• Removed native in-process AI/provider, embeddings/vector retrieval, generated knowledge-base, AI ticket suggestions/replies/feedback, and change-review surfaces.
• Preserved Netclaw AiAssistant SignalR ticket chat, external webhook worklogs, and MCP HTTP/stdio transports.
• Removed pgvector and Microsoft AI/VectorData package references; standard postgres:16 is used for bundled/test PostgreSQL.
• Historical pg_trgm migration creation is now a no-op for fresh installs. Existing installations retain any extension/indexes already present; normal search behavior remains functional without an extension requirement.
• Added forward PostgreSQL and SQLite schema cleanup migrations without dropping extensions or using extension CASCADE.
• Bumped to 0.1.0-rc.7 and updated setup/self-hosting documentation.

Validated the Release test build, PostgreSQL and SQLite migration regressions, external SignalR chat persistence, and MCP catalog/HTTP transport tests.