Hands-on verification of the v0.7.0 release surfaced a set of defects
in the REST layer and the startup/metadata handling. This addresses
all of them; each fix was reproduced against a locally running
emulator before and after, and is covered by a new regression test.

- #333: with --port=0 the startup log printed ":0" instead of the
  OS-assigned port. The server now reports the actually bound HTTP and
  gRPC addresses through a SetListenCallback hook; the CLI prints them
  and the server library writes nothing to stdout itself.
- #237 / #397 / #207: restarting against a persisted database wiped
  or duplicated metadata. The startup loader re-inserted datasets
  unconditionally (UNIQUE constraint violation) and overwrote the
  project datasetIDs with the empty CLI project (datasets vanished
  from the REST catalog). The loader now reconciles source-described
  objects with what is already stored, inserting only what is missing.
- #136 / #396: an upload whose metadata omitted jobReference (the
  Node.js client) dereferenced a nil pointer; uploading to a missing
  dataset panicked. The upload job is normalized (a job id is
  generated when absent) and the missing-dataset case returns 404.
- #339 / #249: tables.get did not populate numRows. It is now filled
  from the backing table row count.
- #293 / #363 / #362 / #412: table updates were broken. tables.patch
  ignored the request body and echoed it back instead of a full Table
  resource; tables.update was an "unsupported" stub; the
  X-HTTP-Method-Override header (used by the Java client) was not
  honored. Patch now shallow-merges and persists, update replaces,
  both return the full resource, and a method-override wrapper runs
  before routing.
- #144: inserting into a JSON column stored a string double-encoded
  and panicked on a native JSON object. JSON columns are now inserted
  via PARSE_JSON, and normalizeData no longer walks a JSON value as a
  STRUCT.
- #347: a load job from gs:// failed with "could not find default
  credentials" when no GCS emulator was configured. The Storage
  client now falls back to anonymous access (honoring
  GOOGLE_APPLICATION_CREDENTIALS when set).
- #392: external tables were created in metadata but never registered
  with the query engine, so querying them failed with "Table not
  found". External table source data is now materialized into a
  backing table through the load pipeline at creation time.

Regression tests for every fix are added to server/server_test.go,
plus server/gcs_internal_test.go for the unexported GCS client
options helper.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>