feat: adds --readonly and --pin flags, and displays Size column in list by default

testdata/meta-decrypt.ct

@@ -1,9 +1,12 @@
 # Decrypt an existing encrypted key
 $ pda set --encrypt hello@md world
 $ pda meta hello@md --decrypt
+  ok decrypted hello@md
 $ pda meta hello@md
   key: hello@md
   secret: false
+  writable: true
+  pinned: false
   expires: never
 $ pda get hello@md
 world