fix(extraction): TS type-alias object members are first-class nodes (#359) (#471)

A call site `recorder.stop()` where `recorder: RecorderHandle` and
`type RecorderHandle = { stop: () => Promise<void> }` used to attach
its edge to an unrelated `class Foo { stop() {} }` in a sibling
directory — there was no `RecorderHandle::stop` node, so the existing
camelCase/path-proximity scoring picked the only `stop` method in the
graph (which happened to be wrong). False-positive `calls` edges
silently widened `codegraph_impact` blast radius.

`extractTypeAlias` now surfaces object-shape (and intersection-type)
members as first-class graph nodes:

  type X = { foo: T; bar(): T };
  ->  X        (type_alias)
      X::foo   (property)
      X::bar   (method)

Function-typed properties (`stop: () => Promise<void>`) emit as `method`
kind so `obj.stop()` resolves to them at the call site — same node
kind the existing receiver-name/word-overlap heuristic in
`matchMethodCall` already prefers. No new resolver logic needed.

Walk only immediate `object_type` / `intersection_type` operands of the
alias value. Anonymous nested object types inside generic arguments
(`Promise<{ ok: true }>`) intentionally don't produce phantom members.

Validation on excalidraw/excalidraw (314 .ts files):
  +776 new property nodes (alias non-function members)
  +1,008 new method nodes (alias function-typed properties + method_signatures)
  +226 calls edges newly accurate against alias members

User's exact 3-file repro:
  before: finaliseRecording -> StdioMcpClient::stop (wrong, sibling dir)
  after:  finaliseRecording -> RecorderHandle::stop (correct)
  StdioMcpClient::stop callers: voice/ false-positives gone

Closes #359.