feat(cli): add pic triggers + dead-letters + secrets subcommands

Closes the audit's High-severity CLI coverage gap, raising the count
from ~25 to ~40+ subcommands and bringing the integration test count
from 63 to 73.

- pic triggers {ls, rm, create-kv, create-cron, create-dead-letter,
  create-from-json}: three per-kind wrappers cover the most common
  trigger shapes; the generic create-from-json is the escape hatch
  for docs/files/pubsub/email/queue and any future advanced retry
  knobs — body JSON inline, via @<file>, or "-" for stdin.

- pic dead-letters {ls, show, replay, resolve}: full operator
  workflow for the dispatcher's dead_letters rows, including the
  --unresolved filter and the per-row replay + manual-resolve actions.

- pic secrets {ls, set, rm}: list names + updated_at, set values
  via stdin (the only secure channel — inline values would leak
  into shell history), and delete by name. --json on set treats
  stdin as raw JSON for non-string values.

Ten new integration tests follow the established #[ignore] pattern,
gated on DATABASE_URL. All 73 ignored tests pass against the local
dev stack.

The `pic admin reset-password` server-binary subcommand exists on
the picloud binary side already; the audit's "surface it in pic
--help" note is a one-line addition deferred to Stage 6 with the
other small UX touches.

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

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

@@ -0,0 +1,55 @@
+//! `pic secrets` subcommands: `ls`, `set`, `rm`.
+//!
+//! Set reads the secret value from stdin (the only safe channel —
+//! inline values would leak into shell history). The value is sent
+//! as a JSON string; pass `--json` to interpret stdin as raw JSON
+//! (numbers, maps, …) instead.
+
+use std::io::Read;
+
+use anyhow::{anyhow, Context, Result};
+
+use crate::client::Client;
+use crate::config;
+use crate::output::{OutputMode, Table};
+
+pub async fn ls(app: &str, mode: OutputMode) -> Result<()> {
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    let resp = client.secrets_list(app).await?;
+    let mut table = Table::new(["name", "updated_at"]);
+    for s in resp.secrets {
+        table.row([s.name, s.updated_at.to_rfc3339()]);
+    }
+    table.print(mode);
+    Ok(())
+}
+
+pub async fn set(app: &str, name: &str, as_json: bool) -> Result<()> {
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    let mut buf = String::new();
+    std::io::stdin()
+        .read_to_string(&mut buf)
+        .context("read secret value from stdin")?;
+    let trimmed = buf.trim_end_matches(['\n', '\r']);
+    if trimmed.is_empty() {
+        return Err(anyhow!("empty stdin — secret value must not be empty"));
+    }
+    let value = if as_json {
+        serde_json::from_str(trimmed).map_err(|e| anyhow!("parse stdin as JSON: {e}"))?
+    } else {
+        serde_json::Value::String(trimmed.to_string())
+    };
+    client.secrets_set(app, name, value).await?;
+    println!("Set secret {name}");
+    Ok(())
+}
+
+pub async fn rm(app: &str, name: &str) -> Result<()> {
+    let creds = config::resolve()?;
+    let client = Client::from_creds(&creds)?;
+    client.secrets_delete(app, name).await?;
+    println!("Deleted secret {name}");
+    Ok(())
+}