feat(vars): admin CRUD API + pic vars CLI

Completes the vars half of Phase 3 end-to-end:
- vars_repo: VarOwner{Group|App} upsert/delete/list (owner-kind-specific
  SQL; ON CONFLICT restates the partial-index predicate).
- vars_api: GET/PUT/DELETE under /apps/{id}/vars and /groups/{id}/vars,
  resolve-then-require gated on App/GroupVars{Read,Write}, secrets-style
  error mapping + key/env-scope validation.
- pic vars ls/set/rm (--group|--app, --env, --json, --tombstone).
- journey test: a group var is inherited by a descendant app's
  vars::get(), and an app-level value overrides it (proximity) — green.

386 manager-core lib tests + the vars journey pass; clippy clean.

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

crates/picloud-cli/src/cmds/mod.rs

@@ -22,4 +22,5 @@ pub mod secrets;
 pub mod topics;
 pub mod triggers;
 pub mod users;
+pub mod vars;
 pub mod whoami;

crates/picloud-cli/src/cmds/vars.rs

@@ -0,0 +1,85 @@
+//! `pic vars ls | set | rm` — manage Phase-3 group/app config vars.
+//!
+//! Wraps `/api/v1/admin/{apps,groups}/{id}/vars*`. Exactly one of
+//! `--group` / `--app` selects the owner. `ls` shows the owner's OWN rows
+//! (not the resolved/inherited view). Set values are JSON strings by
+//! default; `--json` parses the value as raw JSON.
+
+use anyhow::{anyhow, Result};
+
+use crate::client::{Client, VarOwnerArg};
+use crate::config;
+use crate::output::{OutputMode, Table};
+
+/// Resolve the `--group`/`--app` pair into exactly one owner.
+fn owner<'a>(group: Option<&'a str>, app: Option<&'a str>) -> Result<VarOwnerArg<'a>> {
+    match (group, app) {
+        (Some(g), None) => Ok(VarOwnerArg::Group(g)),
+        (None, Some(a)) => Ok(VarOwnerArg::App(a)),
+        (Some(_), Some(_)) => Err(anyhow!("pass exactly one of --group / --app, not both")),
+        (None, None) => Err(anyhow!("pass one of --group / --app")),
+    }
+}
+
+pub async fn ls(group: Option<&str>, app: Option<&str>, mode: OutputMode) -> Result<()> {
+    let owner = owner(group, app)?;
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    let resp = client.vars_list(owner).await?;
+    let mut table = Table::new(["key", "env", "value", "tombstone", "updated_at"]);
+    for v in resp.vars {
+        table.row([
+            v.key,
+            v.env,
+            v.value.to_string(),
+            v.is_tombstone.to_string(),
+            v.updated_at.to_rfc3339(),
+        ]);
+    }
+    table.print(mode);
+    Ok(())
+}
+
+pub async fn set(
+    group: Option<&str>,
+    app: Option<&str>,
+    key: &str,
+    value: &str,
+    env: Option<&str>,
+    as_json: bool,
+    tombstone: bool,
+) -> Result<()> {
+    let owner = owner(group, app)?;
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    // A tombstone carries no value (the server stores JSON null + the
+    // deletion marker); otherwise parse per `--json`.
+    let parsed = if tombstone {
+        serde_json::Value::Null
+    } else if as_json {
+        serde_json::from_str(value).map_err(|e| anyhow!("parse value as JSON: {e}"))?
+    } else {
+        serde_json::Value::String(value.to_string())
+    };
+    client.vars_set(owner, key, parsed, env, tombstone).await?;
+    if tombstone {
+        println!("Set tombstone for {key}");
+    } else {
+        println!("Set var {key}");
+    }
+    Ok(())
+}
+
+pub async fn rm(
+    group: Option<&str>,
+    app: Option<&str>,
+    key: &str,
+    env: Option<&str>,
+) -> Result<()> {
+    let owner = owner(group, app)?;
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    client.vars_delete(owner, key, env).await?;
+    println!("Deleted var {key}");
+    Ok(())
+}