feat: declarative project-tool foundation (pull/plan/apply/prune)

Add a server-side, atomic, declarative reconcile loop for a single app —
the foundation of the project-tool design. Developers describe an app's
scripts, routes, triggers, and secret-names in `picloud.toml`, then
`pic pull / plan / apply [--prune]` to converge live state to the manifest.

Server (manager-core):
- apply_service: a pure diff engine (compute_diff) shared by plan and
  apply, plus an ApplyService that composes the existing per-repo writes
  into ONE Postgres transaction. Identity keys mirror the DB UNIQUE
  constraints (script=lower(name); route=(method,host_kind,host,
  path_kind,path); trigger=per-kind semantic tuple; secret=name).
  Apply takes a per-app advisory lock, recomputes the diff in-tx, applies
  scripts -> routes -> triggers, prunes dependents-first, commits, then
  refreshes the route table once post-commit.
- apply_api: POST /apps/{id}/plan (AppRead) and /apps/{id}/apply.
  Apply requires the per-kind write caps the bundle exercises (all three
  when --prune), plus AppSecretsRead when it binds an email trigger.
- tx-accepting repo siblings (insert/update/delete *_tx) so the existing
  create/update/delete delegate to one SQL definition each.
- email triggers reference an inbound secret by NAME; the value is
  resolved, decrypted (AAD-bound), and re-sealed server-side at apply —
  it never travels in the manifest.

CLI (picloud-cli):
- manifest.rs (picloud.toml model), client plan/apply, and the pull/plan/
  apply commands. pull rejects filesystem-unsafe script names up front.

Safety properties enforced and tested:
- idempotent: a freshly-pulled manifest re-applies as all-NoOp.
- atomic: a mid-bundle failure rolls back with nothing written.
- routes delete-before-insert so a freed binding is reusable in one apply.
- queue one-consumer invariant held inside the shared tx.
- email triggers are never pruned, and a script that still owns an
  email/dead-letter trigger can't be pruned (the FK cascade would destroy
  the sealed secret) — refused with a pointer to `pic triggers rm`.
- plan and apply agree on unset email-secret references.

No migration: the existing schema's UNIQUE constraints serve as identity
keys. Groups, env-scoping, and the `enabled` toggle are later milestones.

Tested: manager-core lib (360) + CLI bins (27) + 8 project-tool journeys
(pull/plan/apply/prune/email+queue), all green; clippy -D warnings clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/manager-core/src/route_admin.rs

@@ -426,7 +426,7 @@ fn compile_route(r: &Route) -> Result<CompiledRoute, pattern::ParseError> {
 /// Validate that a new route's (host_kind, host) is consistent with at
 /// least one of the parent app's domain claims. `HostKind::Any` is
 /// always permitted — it catches every host the app already owns.
-async fn validate_route_host_against_app(
+pub(crate) async fn validate_route_host_against_app(
     domains: &dyn AppDomainRepository,
     app_id: AppId,
     host_kind: HostKind,