feat: configure stopped-room polling and separate runtime types

[bandzalkin]

Why

Stopped rooms probe /next at the base reconciliation interval indefinitely to discover missed PLAY controls. Hosts need to reduce that polling volume without slowing active-room recovery. Session tunables need consistent typed validation and environment configuration, and runtime types need clear ownership.

What

• Add SessionConfig.stopped_resync_seconds for fixed stopped-room polling, falling back to the base interval when unset.
• Migrate all of SessionConfig to Pydantic settings. Explicit keyword arguments override case-insensitive environment values; empty values use defaults. Reconciliation intervals share positive, finite constraints and existing working-state timing rules remain enforced.
• Split runtime configuration, messages, conversation context, contacts, callbacks, and handle formatting into their owning modules. Remove runtime/types.py and update SDK callers, the bridge, examples, tests, and README imports directly. Record the import-ownership rule in AGENTS.md.
• Preserve earlier armed deadlines on STOP and restore base cadence on PLAY. Cadence tests observe HTTP requests under virtual loop time.

Scope

Quiet-room backoff, startup/reconnect reconciliation, and control fencing are unchanged. The configuration migration intentionally makes SessionConfig construction keyword-only and serialization use model_dump(). The old band.runtime.types import path is removed without compatibility aliases. Other runtime configuration behavior is unchanged.

[AlexanderZ-Band]

Three verified issues: required-interval validation regression, constructor coverage bypass, and missing Pydantic settings for the new knob. Applying focused fixes.

All three findings were fixed in 2ef3238 and their threads resolved. Final review found no remaining verified defects; lint, formatting, type checks, full unit suite, and focused post-change regressions passed.

[AlexanderZ-Band]

issue: Current-main callers in tests/adapters/lifecycle/test_runtime_closing.py:10 and tests/integrations/acp/test_cursor_message_delivery.py:12 still import deleted band.runtime.types. The synthetic merge fails collection on Ubuntu and Windows. Migrate both imports to band.runtime.sessionconfig after updating the branch to current main.

[AlexanderZ-Band]

Fresh full review found no additional verified defects. One direct-owner import nit remains in callbacks.py.

[AlexanderZ-Band]

Fixed the collection finding in e0b7f5a. The branch now includes current main, and both tests added there import SessionConfig from band.runtime.sessionconfig. The original two collection errors reproduce before the fix; all 11 affected test cases pass afterward. The full suite on the rebased tree passed 8,723 tests, and Ruff, formatting, Pyrefly and markdown checks pass. The direct-owner import nit is also fixed and its thread resolved. The review converged after two passes with no remaining verified defect.

The synthetic-merge collection defect is fixed in e0b7f5a after updating the branch to current main and migrating both callers. The original failure no longer reproduces; affected tests and full local gate passed. Final review found no remaining verified issue.

[AlexanderZ-Band]

Fresh my-code-review --fix completed against aeb2844. One review cycle converged with no verified findings across all six angle groups; no unresolved existing feedback. Reviewed stopped-room polling, Pydantic SessionConfig settings, and direct imports after deleting runtime/types.py, including the intentional API changes. Simplify only shortened two timing comments. Validation: 8,723 unit tests passed, Ruff check and format check passed, and Pyrefly passed. Live platform timing was not exercised. No linked Linear ticket was found.

[AlexanderZ-Band]

All verified findings are fixed. The fresh six-angle review found no remaining defects or unresolved feedback. Local validation passed 8,723 tests plus Ruff, formatting, and Pyrefly. CI is complete: 27 passed, 1 skipped.