feat(gateway): persist mobile mutation receipts

[ericlewis]

Stack

This draft is stacked on #62858 (feat/mobile-contract-hello-scopes). It intentionally includes that PR's commits until #62858 merges; rebase this branch onto main after the parent lands.

• Parent head used: d8bc3bc9b1277b54d72b097c7a5d0328ecb62348
• Parent base: f67aae323010e32c592a185984d36b20e9fa474a
• This foundation implements the non-approval durable-mutation work tracked in ericlewis/cuttle#4.

Summary

• persist mobile mutation receipts in a private SQLite store keyed by authenticated principal plus client request identity
• fingerprint durable Hermes conversation identity and semantic parameters rather than replaceable live session IDs
• require client_request_id for mobile prompt submission, interruption, and deletion while preserving legacy ID-less transports
• replay identical completed requests with deduplicated: true, reject semantic ID reuse deterministically, and expose authoritative mutation.status
• retain replay after process restart, live-session rotation, and conversation deletion; abandoned ownership becomes fail-closed outcome_unknown
• complete prompt receipts only after the exact principal-scoped user turn is proven persisted by the real SessionDB path
• coordinate deferred prompt receipts with one condition-driven monitor per live session, O(1) live/durable proof sets, exact handoff cleanup, and terminal-only transcript fallback
• preserve durable proof through Hermes consecutive-user repair without falsely promoting an unpersisted row
• terminalize queued mobile prompts canceled by interrupt rather than leaving an in-progress receipt or live-tag residue

Existing dashboard, stdio, messaging, and other legacy callers keep their current wire behavior. The capability advertises only the mutation methods implemented in this slice.

Validation

Clean commit cc535c21eb6c98a778d88f27d8d76cad096fa964:

• all 30 tests/tui_gateway/test_*.py files in fresh process isolation: 420 passed
• tests/test_tui_gateway_server.py: 316 passed
• dashboard auth WebSocket: 61 passed
• dashboard ticket WebSocket: 23 passed
• root gateway WebSocket: 6 passed
• console WebSocket: 5 passed
• PTY keepalive WebSocket: 1 passed
• tests/run_agent/test_run_agent.py: 416 passed
• chat-completions transport: 88 passed
• turn context: 15 passed
• message-sequence repair: 39 passed
• total distinct coverage: 1,390 passed, 0 failed
• two independent final reviews: no findings
• Ruff on all changed Python files: passed
• git diff --check: passed
• added-line cross-platform footgun scan: clean

The tests/tui_gateway files are intentionally invoked in fresh processes because current upstream test_inline_rpc_gil_starvation.py replaces the global prompt.submit handler without restoring it; file-scoped isolation avoids that unrelated cross-file test leak.

Deliberate limit / next stack

approval.respond is intentionally not advertised by this foundation branch. Stable approval identity, recoverable lifecycle events, and durable approval-response fingerprinting are integrated together on the next #5 stack; ericlewis/cuttle#4 remains open until that integration is published and validated.