feat: secrets CLI MVP — add/search/delete with PostgreSQL JSONB

- Single `secrets` table with namespace/kind/name/tags/metadata/encrypted
- Auto-migrate on startup using uuidv7() primary keys and GIN indexes
- CLI commands: add (upsert, @file support), search (full-text + tags), delete
- Multi-platform Gitea Actions: debian (x86_64-musl), darwin-arm64, windows
  - continue-on-error + timeout-minutes=30 for offline runner tolerance
- VS Code tasks.json for local build/test/seed
- AGENTS.md for AI context

Made-with: Cursor

src/commands/delete.rs

@@ -0,0 +1,20 @@
+use anyhow::Result;
+use sqlx::PgPool;
+
+pub async fn run(pool: &PgPool, namespace: &str, kind: &str, name: &str) -> Result<()> {
+    let result = sqlx::query(
+        "DELETE FROM secrets WHERE namespace = $1 AND kind = $2 AND name = $3",
+    )
+    .bind(namespace)
+    .bind(kind)
+    .bind(name)
+    .execute(pool)
+    .await?;
+
+    if result.rows_affected() == 0 {
+        println!("Not found: [{}/{}] {}", namespace, kind, name);
+    } else {
+        println!("Deleted: [{}/{}] {}", namespace, kind, name);
+    }
+    Ok(())
+}