Redefine request-retry as additional credential retry rounds and
enforce max-retry-credentials per round. Home dispatch now carries
excluded and pinned auth constraints, supports remote retry limits, and
propagates cooldown retry-after metadata across exhausted rounds.
Move Antigravity upstream retries under conductor ownership to avoid
double-consuming retry attempts. Update configuration comments and add
coverage for Home retry rounds, cooldown handling, pinned credentials,
and legacy dispatcher compatibility.
- Removed deprecated interceptor and executor-related methods, including `callRequestInterceptor`, `callResponseInterceptor`, and `callStreamChunkInterceptor`.
- Consolidated unused logic and pruned redundant imports to streamline `adapters.go`.
- No functional changes.
