feat(project-tool): bound-plan staleness check (content fingerprint)

`pic plan` now records a fingerprint of the live state it diffed against;
`pic apply` replays it and the server refuses (HTTP 409) if the app
changed underneath the reviewed plan — the §4.2 "apply exactly what you
reviewed" guarantee, in its content-addressed form (no migration, no
changes to interactive write paths).

Server (manager-core):
- `state_token(CurrentState)`: deterministic FNV-1a fingerprint over what
  the diff keys on — script name+version (version bumps on any edit),
  route identity+binding/attrs, trigger membership+enabled, secret names.
  Order-independent; a collision can only yield a false "unchanged", never
  a false refusal.
- `plan` returns it (flattened onto the plan JSON, so the wire stays
  additive); `apply` takes an optional `expected_token` and, under the
  apply lock before any write, returns `StateMoved` (409) on mismatch.

CLI:
- `.picloud/` link state (`linkstate`): `pic plan` writes the token scoped
  to the app slug; `pic apply` replays it, then clears it on success (the
  token is single-use — the next apply re-plans). `--force` skips the
  check; apply with no recorded plan still works standalone (today's
  behavior). `.picloud/` is already gitignored by `pic init`.

The tree-structure version (the other half of §4.2's counter) stays a
deliberate no-op until groups exist — it only guards reparent/structural
moves, which don't exist single-app.

Tested: state_token unit test (stable/order-independent/sensitive) + a
staleness journey (plan → out-of-band deploy → apply refuses → --force
applies); manager-core lib 363 + cli bins 31 + 13 journeys green; clippy
-D warnings clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/picloud-cli/tests/cli.rs

@@ -31,4 +31,5 @@ mod roles;
 mod routes;
 mod scripts;
 mod secrets;
+mod staleness;
 mod triggers;

crates/picloud-cli/tests/init.rs

@@ -68,7 +68,10 @@ fn init_appends_to_an_existing_gitignore_once() {
         .assert()
         .success();
     let gitignore = fs::read_to_string(dir.path().join(".gitignore")).unwrap();
-    assert!(gitignore.contains("target/"), "must preserve existing rules");
+    assert!(
+        gitignore.contains("target/"),
+        "must preserve existing rules"
+    );
     assert_eq!(
         gitignore.matches(".picloud/").count(),
         1,

crates/picloud-cli/tests/staleness.rs

@@ -0,0 +1,82 @@
+//! Bound-plan staleness: `pic plan` records a state token under `.picloud/`,
+//! and a later `pic apply` refuses (without `--force`) if the app changed
+//! out-of-band since the plan was reviewed.
+
+use std::fs;
+
+use tempfile::TempDir;
+
+use crate::common;
+use crate::common::cleanup::AppGuard;
+
+#[ignore = "needs DATABASE_URL pointing at a running Postgres"]
+#[test]
+fn apply_refuses_when_state_moved_since_plan() {
+    let Some(fx) = common::fixture_or_skip() else {
+        return;
+    };
+    let env = common::admin_env(fx);
+    let slug = common::unique_slug("stale");
+    common::pic_as(&env)
+        .args(["apps", "create", &slug])
+        .assert()
+        .success();
+    let _guard = AppGuard::new(&env.url, &env.token, &slug);
+
+    let dir = TempDir::new().unwrap();
+    fs::create_dir_all(dir.path().join("scripts")).unwrap();
+    fs::write(dir.path().join("scripts/hello.rhai"), "let x = 1; x").unwrap();
+    let manifest_path = dir.path().join("picloud.toml");
+    let manifest = format!(
+        "[app]\nslug = \"{slug}\"\nname = \"Stale\"\n\n\
+         [[scripts]]\nname = \"hello\"\nfile = \"scripts/hello.rhai\"\n"
+    );
+    fs::write(&manifest_path, &manifest).unwrap();
+
+    // Establish hello, then plan — the plan records the current state token.
+    apply(&env, &manifest_path).assert().success();
+    common::pic_as(&env)
+        .args(["plan", "--file"])
+        .arg(&manifest_path)
+        .assert()
+        .success();
+    assert!(
+        dir.path().join(".picloud/plan.json").exists(),
+        "plan must record the bound-plan token under .picloud/"
+    );
+
+    // Out-of-band change: deploy an extra script the manifest doesn't mention.
+    fs::write(dir.path().join("scripts/sneaky.rhai"), "let y = 2; y").unwrap();
+    common::pic_as(&env)
+        .args(["scripts", "deploy"])
+        .arg(dir.path().join("scripts/sneaky.rhai"))
+        .args(["--app", &slug])
+        .assert()
+        .success();
+
+    // Apply must now refuse — the live state no longer matches the plan.
+    let refused = apply(&env, &manifest_path).output().expect("apply");
+    assert!(
+        !refused.status.success(),
+        "apply must refuse after out-of-band change"
+    );
+    let err = String::from_utf8_lossy(&refused.stderr);
+    assert!(
+        err.contains("changed since") || err.contains("pic plan"),
+        "refusal should explain the staleness:\n{err}"
+    );
+
+    // `--force` bypasses the check and applies anyway.
+    common::pic_as(&env)
+        .args(["apply", "--file"])
+        .arg(&manifest_path)
+        .arg("--force")
+        .assert()
+        .success();
+}
+
+fn apply(env: &common::TestEnv, manifest_path: &std::path::Path) -> assert_cmd::Command {
+    let mut cmd = common::pic_as(env);
+    cmd.args(["apply", "--file"]).arg(manifest_path);
+    cmd
+}