v0.20.1 — fix indirect call detection for array subscript expressions

Overview

Patch release fixing find_indirect_call_sites for array-subscript
function pointer calls — the primary dispatch pattern in embedded
firmware (ISR vector tables, callback arrays, state machine dispatch).
Also surfaces indirect call sites in get_symbol_context for function
and method symbols.

Changes

Fixes

• Array subscript indirect call detection — handlers[irq](arg),
  obj->callbacks[idx](args), and similar patterns are now detected as
  indirect call sites. Previously cursor.referenced was None for
  ArraySubscriptExpr callees, so the call site was silently missed.
• get_symbol_context for functions — indirect_call_sites field is
  now populated for function and method symbols (via from_usr
  query), not only for field and variable symbols.

File	Change
src/fw_context_mcp/indexer/symbols.py	_first_child_unwrapped helper + ArraySubscriptExpr fallback in indirect call site extraction
src/fw_context_mcp/mcp/handlers/source.py	from_usr query for function/method indirect call sites in get_symbol_context
tests/test_db.py	4 tests: array subscript, struct array member, no false positives, member access regression

Breaking changes

None.