Namespace MCP tools with domain prefixes for discoverability

[jafreck]

Problem

All 17 MCP tools use a flat lore_* namespace. When agents enumerate available tools, the list gives no indication of domain grouping — lore_blame sits next to lore_docs with no structural hint that one is git-related and the other is documentation-related.

Proposal

Rename tool names with domain prefixes:

Current	New	Domain
lore_lookup	lore_code_lookup	Code structure
lore_search	lore_code_search	Code structure
lore_snippet	lore_code_snippet	Code structure
lore_annotations	lore_code_annotations	Code structure
lore_routes	lore_code_routes	Code structure
lore_graph	lore_graph	Graph (cross-cutting)
lore_architecture	lore_architecture	Graph (cross-cutting)
lore_docs	lore_docs	Docs
lore_blame	lore_git_blame	Git
lore_history	lore_git_history	Git
lore_coverage	lore_test_coverage	Testing
lore_test_map	lore_test_map	Testing
lore_metrics	lore_metrics	Metrics
lore_notes_read	lore_notes_read	Agent memory
lore_notes_write	lore_notes_write	Agent memory
lore_writeback	lore_notes_writeback	Agent memory

Implementation notes

• Each tool's toolDef.name in src/lore-server/tools/*.ts is the single source of truth — update those strings.
• No deprecation aliases or backwards compat — old names are removed outright.
• Update docs/architecture.md and README.md tool tables.

Acceptance criteria

• All tool names follow the lore_{domain}_{action} pattern where a domain grouping applies
• Old names are fully removed (no aliases)
• Architecture docs and README updated
• Tests updated for new names