feat(tools): add lore_dependents tool for unified reverse-dependency queries

[jafreck]

Summary

Implements #178 — adds a new lore_dependents MCP tool that answers "what is affected if I change X?" in a single call.

Changes

New: src/server/tools/dependents.ts

• Name-based input: takes a symbol name or file path (not numeric IDs), resolves internally
• Cross-kind aggregation: returns callers, importers, subclasses, and type_references in one response
• Transitive closure: depth param (1–5) follows dependents N hops deep via frontier expansion
• Compact mode: compact: true strips provenance fields (line, character, resolution_method) to reduce tokens
• Branch filtering: optional branch param filters all queries
• Disambiguation: ≤5 symbol matches aggregates results; >5 returns error with candidates

Modified: src/server/tool-registry.ts

• Registered lore_dependents in buildToolModules()

New: tests/server/tools/dependents.test.ts

• 25 tests covering: toolDef shape- 25 tests covering: toolDef shape- 25 tests covering: toolDef shape--fi- 25 tests covering: toolDef shape- 25 tests covering: toolDef shape- 25 tests covering: toolDef shape--fi- 25 tests covele
• 25 testlor- 25 testlor- 25 testlor- 25 testlor- 25: - 25 testlor- 25 testlor- 25 testlor- 25 testlor- 25: - 25 testlor- 25 testlor- 25 testlor- 25d"- 25 testlor- 25 testlor- 25 testlor- 25 testlor- 25: - 25 testlor- 25 testlor- 25 testlor- 25 testlor- 25: - 25 - 25 testlor- 25 testlor- 25 testlor- 25 testlor- 25: - 25 testlor- 25 testlor- 25 testlor- 25 testl}

Closes #178

[codecov]

Codecov Report

❌ Patch coverage is 96.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.23%. Comparing base (4e3123d) to head (3fb3f70).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/server/tools/dependents.ts	95.97%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #204      +/-   ##
==========================================
+ Coverage   88.10%   88.23%   +0.13%     
==========================================
  Files          79       80       +1     
  Lines        8870     9020     +150     
  Branches     2764     2791      +27     
==========================================
+ Hits         7815     7959     +144     
- Misses       1055     1061       +6     

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