feat(apply): server-side enforcement of per-env approval gating (§3 M3 / §4.2)

The per-env approval gate (`[project.environments]`, `confirm = true`) was
client-side only — the policy was `#[serde(skip_serializing)]`, so a patched or
older CLI applying to a confirm-required env bypassed it entirely. This makes
the gate server-enforced, admin-gated, and audited (the deferred §4.2 piece).

- Wire: `ProjectDecl` gains `environments` (the CLI stops skip_serializing it and
  sends the selected `env` + the `--approve` set on the apply request). The
  server RE-DERIVES the gate from the request (`env_gate_check`): a
  confirm-required env not in `approved_envs` → 409 `ApprovalRequired`.
- Admin gate: an approved override additionally requires `AppAdmin`/`GroupAdmin`
  on EVERY declared node — a step up from the editor write caps an ordinary
  apply needs (reusing the admin caps per §4.2) — and emits a `tracing::info!`
  audit line. Enforced on all three handlers (single app, single group, tree);
  the check runs before any tx, so a denial (403) precedes any mutation.
- Token: the env policy folds into the TREE bound-plan token (a policy edit
  between plan and apply trips StateMoved). The single-node token is left
  unchanged (a bare live-state hash), so plan/apply still match without threading
  a project into it.
- CLI: single-node `apply`/`plan` now resolve the GOVERNING project (own block
  else nearest ancestor's) so a leaf apply carries the root's policy; `plan`
  surfaces `approvals_required`. Client-side `require_env_approval` fast-fail
  kept as UX.

Adapts the earlier feat/ownership-and-approval M5 (654e387) to main's DTOs; main
addresses tree group nodes by slug only, so the admin loop mirrors authz_tree
(app: resolve_app_id fail-closed; group: get_by_slug, skip to-create).

Threat-model note (honest scope, in the doc + code comments): this closes the
patched/older-CLI bypass and admin-gates + audits the override, but is NOT a
hermetic boundary against a hand-crafted request that OMITS the policy — the
policy is applier-supplied, not persisted server state. Full closure (persist a
`project_environments` source of truth + a server-determined env) is deferred.

Review (adversarial pass): fixed a MEDIUM (single-node `plan` didn't resolve the
governing project, so a leaf plan under-reported the gate `apply` enforces) and a
LOW (duplicate clippy attr); corrected overstated "can't bypass" wording.

Tests: ProjectDecl gate unit test; env_approval journeys
`server_enforces_the_gate_against_a_non_stock_client` (raw request → 409 without
approval, admin-approved → 200) and `approving_a_gated_apply_requires_admin`
(editor + --approve → 403). 417 lib tests + 33 CLI journeys + workspace clippy
-D warnings + fmt clean. No migration.

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

crates/picloud-cli/src/manifest.rs

@@ -286,9 +286,15 @@ pub struct ManifestProject {
     /// §3 M3 per-env approval policy: `[project.environments]` maps an env name
     /// to its policy. A `confirm = true` env requires an explicit `--approve
     /// <env>` on `pic apply --env <env>` (a blanket `--yes` does NOT cover it —
-    /// §4.2 "CI must opt in per environment"). Client-side gating only; never
-    /// sent to the server.
-    #[serde(default, skip_serializing)]
+    /// §4.2 "CI must opt in per environment"). The CLI gates client-side (fast
+    /// fail) AND sends the policy to the server, which re-derives the gate from
+    /// the request and enforces it (admin-gated on every declared node + audited).
+    /// This closes the "patched/older CLI that still declares the project but
+    /// skips the local check" bypass; it is NOT a hermetic boundary against a
+    /// request that omits the policy entirely (the policy lives in the applier's
+    /// manifest, not persisted server state — full closure would persist it).
+    /// Sent only when non-empty (pre-M3 wire otherwise).
+    #[serde(default, skip_serializing_if = "std::collections::BTreeMap::is_empty")]
     pub environments: std::collections::BTreeMap<String, EnvPolicy>,
 }