Add first-party built-in tools and attachment ingestion #53

Problem

The product needs a built-in tool layer for file navigation, search, logs, repo status, and attachment normalization before providers can use the environment effectively.

Scope

• Track built-in tools for files, search, logs, repo status, and session recall
• Track attachment ingestion for files, folders, screenshots, diffs, and reports
• Keep the normalized payload shape provider-agnostic

Out of scope

• MCP registry management
• RagSharp indexing internals outside how built-in tools consume repo knowledge

Implementation notes

• Make attachments and built-in tools first-class shared capabilities
• Keep the issue aligned with later provider and audit flows
• Support coding and non-coding sessions

Definition of Done

• The issue defines the minimum built-in tools and attachment types the product must support
• The attachment normalization contract is explicit enough for later implementation

Verification

• Review the issue against the feature spec and provider-composition issues

Dependencies

• Parent epic: [Epic] Build a unified tool and knowledge layer #17