feat: end-to-end script CRUD + Rhai execution

Brings the MVP feature set online: upload a Rhai script, get an HTTP
endpoint that runs it sandboxed in-process, list/update/delete it, and
have invalid sources rejected at upload time. Verified live through
Caddy with a full lifecycle (`create → list → get → execute → update
→ delete`) plus error paths (syntax error, duplicate name, deleted).

Layout — every concern lands behind the trait seam its layer owns, so
cluster-mode in v1.3+ is a swap of two impls, not a rewrite:

  * shared::ScriptValidator — manager calls into validation without
    a hard dep on executor-core; executor-core impls the trait on
    `Engine`. Pinned in shared so neither crate has to know about
    the other.

  * executor-core::Engine — real Rhai engine: sandbox limits (max
    operations / string size / map size / call depth), disabled
    `print`, blocked `import` (DummyModuleResolver), `log::trace
    /info/warn/error` registered as a static module with shared
    log-capture buffer (no `log::debug` because `debug` is a Rhai
    reserved keyword — `log::trace` covers the same need).

      - `ctx` is pushed as a Scope constant exposing
        execution_id, script_id, script_name, request_id,
        invocation_type, request.{path,headers,body}.

      - Response convention: a Map with `statusCode` is the
        structured shape (`{statusCode, headers?, body}`); any
        other return value is a 200 with the value as the body.

      - Engine::execute is now synchronous (pure compute); the
        async wrapper + wall-clock timeout live in
        LocalExecutorClient, which spawns_blocking and applies a
        300s hard ceiling regardless of per-script config.

      - 10 unit tests cover validate, exec, structured response,
        ctx exposure, log capture, op-budget enforcement, runtime
        errors, blocked imports, JSON round-tripping.

  * manager-core::repo — full sqlx CRUD over the `scripts` table,
    with proper unique-violation handling for duplicate names.
    Embedded migrations via `sqlx::migrate!` (one initial
    `0001_init.sql` for pgcrypto + scripts + execution_logs).

  * manager-core::api — `admin_router` mounts `/scripts` and
    `/scripts/{id}`. Create + Update validate source through the
    injected `ScriptValidator` before persistence. Returns proper
    422/409/404 status codes via `ApiError::IntoResponse`.

  * orchestrator-core::api — `data_plane_router` mounts
    `/execute/{id}`: resolves the script through `ScriptResolver`,
    constructs the `ExecRequest` from headers+body, awaits
    `ExecutorClient::execute(..., timeout)`, translates the
    `ExecResponse` to an axum `Response` with header passthrough.
    Maps `ExecError` variants to 422/504/502/507.

  * picloud all-in-one — opens the pool, runs migrations, builds
    one engine, nests both routers under `/api/admin` and `/api`,
    enables structured JSON tracing and graceful shutdown on
    SIGTERM. Single `PostgresScriptRepository` Arc is shared by
    the admin router (writes) and the resolver (reads).

Other changes:
  * Workspace axum bump 0.7 → 0.8 for the `{id}` path syntax
    matching the route definitions.
  * Workspace clippy: allow `needless_pass_by_value` and
    `boxed_local` to keep API ergonomics over pedantic noise.

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

Cargo.toml

@@ -27,7 +27,7 @@ picloud-manager-core = { path = "crates/manager-core" }
 
 # Async + HTTP
 tokio = { version = "1.40", features = ["full"] }
-axum = "0.7"
+axum = "0.8"
 tower = "0.5"
 tower-http = { version = "0.6", features = ["trace", "cors"] }
 hyper = "1"
@@ -71,6 +71,10 @@ module_name_repetitions = "allow"
 missing_errors_doc = "allow"
 missing_panics_doc = "allow"
 doc_markdown = "allow"
+# API ergonomics: we deliberately take values by ownership for owned
+# inputs (e.g. ExecRequest) and accept Rhai's Box<EvalAltResult> as-is.
+needless_pass_by_value = "allow"
+boxed_local = "allow"
 
 [profile.release]
 lto = "thin"