feat(v1.1.1-dispatcher): dispatcher loop + retry + depth limit + outbox emitter

`OutboxEventEmitter` replaces `NoopEventEmitter` in the picloud
binary's `Services` bundle. KV mutations now fan out to the outbox
via `TriggerRepo::list_matching_kv` — one row per matching trigger,
carrying the serialized `TriggerEvent` payload + the matching
trigger's retry policy.

`Dispatcher` is the single tokio task that polls the outbox every
100ms, claims due rows via FOR UPDATE SKIP LOCKED (with a batch cap),
and routes each to the executor. Shares the `ExecutionGate` with
sync HTTP per design notes §2 — gate saturation reschedules the
row instead of dropping it.

Outcome handling matches design notes §3 and §4:
- reply_to.is_some() (sync HTTP): never retry. Deliver via
  `InboxResolver`; if the receiver was dropped, write an
  `abandoned_executions` row.
- is_dead_letter_handler == true: never retry, never DL. On
  failure, annotate the original DL row with
  `resolution = 'handler_failed'`. Stops the recursion that would
  otherwise re-fire a broken handler script.
- Otherwise async: bump attempt_count, reschedule with exponential
  backoff + ±jitter; once max_attempts is reached, write a
  `dead_letters` row and drop from outbox.
- Trigger-depth limit: `cx.trigger_depth > max_trigger_depth` skips
  execution entirely (log + future metric), NEVER dead-letters.
  Loops are not retried via the DL chain — they're terminated.

`InboxResolver` trait lands in `picloud-shared` with a
`NoopInboxResolver` bootstrap that flags every delivery as
`Abandoned`. Commit 6 replaces the noop with the real
in-process registry in `orchestrator-core`.

`AdminPrincipalResolver` builds a `Principal` from a trigger's
`registered_by_principal` user id so the dispatched script executes
as the trigger registrant (design notes §4).

Unit tests cover backoff math (exponential/linear/constant) +
jitter range + ExecError → InboxFailureKind classification + the
status-code table mapping. Integration tests for the full
dispatcher loop need a real Postgres + executor; reviewer runs them
via the manual smoke flow in the plan / HANDBACK.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Cargo.lock

@@ -1605,6 +1605,7 @@ dependencies = [
  "base64",
  "chrono",
  "data-encoding",
+ "picloud-executor-core",
  "picloud-orchestrator-core",
  "picloud-shared",
  "rand 0.8.6",