feat(orchestrator): enroll new human assignments in continuity by default

[ddonathan]

Draft: independent review repairs and installed-effectiveness measurement are pending. Tests do not prove fewer manual nudges in production.

Why

Evidence audit of Dan's replies on both hosts (Linux bw-hq-linuxws01, SQL THQ-HQ-SQL02):

1. Linux: explicit restart nudges in 4 inspected threads ('keep working' 19:59 in CI Rework and in the continuity thread itself, 'sorry continuie', repeated 'Continue where you left off.'). One thread ended with 'Nothing will wake this thread automatically' and ready work left.
2. Linux: at least 7 short next-step replies in one thread where the agent had stopped at choice menus with ready work.
3. SQL: 'keep going' / 'what's left?' / 'how's it going?' nudges in 5 threads; most other restarts there are scheduled continuations, not Dan typing.
4. Inspected Linux parents were unenrolled while the local continuity source defaulted enrollment off. SQL lacks the local feature; missing/null records there do not establish that the setting caused its stops.

Change

1. workContinuityAutoEnroll decoding default: false -> true (packages/contracts/src/settings.ts). Guards unchanged: only Dan-origin web/mobile, non-scheduled, non-child, non-plan, non-settled/snoozed/archived threads enroll; max 3 checks; per-thread opt-out unchanged; MCP still cannot enable it.
2. Own-agent settle now clears continuity before turn end, so supervision cannot spend a check resurrecting a settling thread. The existing runtime settle test hung (120s) without this.
3. ws.ts: tolerate optional creationSource on continuity commands. Pre-existing type error on this branch, fixed so server typecheck is green.

Proof

1. New regression: 'auto enrollment is on by default and spends exactly one check after a missing terminal report' (checks 3->2, exactly one synthetic run).
2. Exclusion suites (server/mcp/provider, plan/child/archive/snooze/paused-goal/scheduled/sender) now seed unenrolled explicitly and still prove every guard with enrollment on.
3. runtimeLayer.test.ts + environment handlers: 129/129 pass. Continuity subset: 54/54. Contracts settings: 167/167.
4. Server and contracts typecheck: 0 errors. Lint on touched files: 0 errors (3 warnings, identical on base).

Not fixed (by design)

Failed/cancelled/session-limit terminals still write blocked instead of retrying; scheduled/MCP-origin threads stay excluded; waits only wake on delegated-task/PR events; allowance still exhausts after 3 silent endings.

Effectiveness after install is not yet measured. This PR is against the fork continuity branch because the continuity feature is not in upstream main yet.

Review R35 found pending-settle supervision loss, sparse legacy opt-out compatibility and proof gaps. Repairs are in progress. Default policy and core continuation are separate layers; upstream submission and readiness wait for demonstrated installed effectiveness.