v2.4.11

Fourth slice of the 2026-04-19 audit fix wave. Closes the remaining
quick-wins; the real 2.5.0 work (CE warmup off the latency deque,
top-heavy rollout MCP tool, competitor bench rerun) is still queued.

Fixed

• db/init_schema.sql at the repo root is now a symlink to the
  packaged canonical at src/agentmemory/db/init_schema.sql. Before
  2.4.11 the root copy drifted 566+ lines behind the packaged schema
  because release builds regenerated only one. A symlink makes drift
  structurally impossible while keeping every existing reference path
  (tests, docs, dev checkout discovery in cmd_init) working.
• tool_memory_search validates borrow_from against scope.
  Cross-agent borrow restricts the SQL to scope='global' internally;
  combining it with an explicit non-global scope produced an
  impossibly-False predicate and silent 0 results before 2.4.11. Now
  returns a clear error naming the incompatibility.
• CLAUDE.md corrected to describe the actual migration layout:
  49 numbered migrations + one unnumbered V2-4 quantum-schema file
  occupying the gap at 050. The quantum file doesn't match the
  runner's ^\d+_.+\.sql$ pattern and must be applied manually on
  fresh installs that want the quantum columns (audit I28).

Changed — hygiene

• Added a comment block above the legacy schema_version (singular)
  table in init_schema.sql explaining why it coexists with the
  runner's schema_versions (plural) tracker — 10 migration files
  write to the singular form and the "append-only" convention means
  we keep the compatibility rather than rewrite them (audit I27).

Testing

1876 passed, 28 skipped, 2 xfailed locally. Two new regression tests
at tests/test_audit_2_4_11_regressions.py lock the symlink structure
and the borrow_from scope guard.