Unify personal search and organise projects and deliverables

Priority: P1 (build on the foundation).

Useful information is scattered across conversations and services. The user needs to find it and turn it into durable work.

Acceptance criteria

• Search owned mail, calendar, notes, documents, files, bookmarks, conversations and completed tasks through one assistant entry point.
• Return source links, dates and permission-scoped excerpts; state when a source is unavailable or stale.
• Group related conversations, people, files, decisions and tasks into a project without duplicating their records.
• Turn a conversation into a note, document or confirmed task and preserve its source connection.
• Create reusable deliverables with discoverable names, versions and links instead of burying the only copy in chat.
• Evaluate retrieval with realistic exact and semantic questions and cross-account/deleted-source tests; add embeddings only if measured gaps justify them.

Dependencies and boundaries

Build on #1472 for indexing rather than duplicate its work. Related #1443 and #1458.

Implementation approach

Audit current main first: some foundations and recent fixes already exist. Close remaining user-visible gaps and preserve working behaviour. This issue records the personal-assistant product backlog, not a claim that every underlying capability is absent. Add focused regression coverage for the behaviour changed.

Start by auditing the current main branch and the indexing foundation from #1472; also review related issues #1443 and #1458. Map which acceptance criteria already work, then focus on one remaining user-visible gap and add regression coverage for the changed behavior, including relevant retrieval and source-availability cases.