test(table): characterize the single-row route before migrating it

The single-row surface (GET/PATCH/DELETE) had no route-level tests despite
being the hottest table write path. Pin the behavior it emits today so the
migration onto the shared internal route builder is verifiable rather than
hopeful.

Covers status codes, body shapes, ISO-8601 timestamp serialization, the
access level each method demands, collaborator invocation, and the
dual-caller wire keying — session callers pass column ids through untouched
while internal-JWT callers translate names to ids in both directions.

Verified to fail: mutating the wire translator, the deleted count, and the
workspace-ownership guard each turn the corresponding tests red.

Author: waleedlatif1