ci: add stale PR workflow with 30-day window

[dev-jodee]

Summary

• Add a stale PR workflow matching the escrow/rewards repos
• Marks PRs stale after 30 days of inactivity, closes 5 days later
• Issues are exempt (days-before-issue-stale: -1)

[github-actions]

Compute Unit Report

Instruction	Samples	Min CUs	Max CUs	Avg CUs	Est Cost (Low) [SOL]	Est Cost (Med) [SOL]	Est Cost (High) [SOL]
cancel_subscription	22	1720	2030	1919	0.000005000	0.000005076	0.000005959
close_subscription_authority	10	1803	1833	1806	0.000005000	0.000005072	0.000005903
create_fixed_delegation	41	3522	11022	5155	0.000005001	0.000005206	0.000007577
create_plan	97	3436	11705	4846	0.000005001	0.000005193	0.000007423
create_recurring_delegation	29	3550	12555	5470	0.000005001	0.000005218	0.000007735
delete_plan	9	359	359	359	0.000005000	0.000005014	0.000005179
init_subscription_authority	173	6226	18226	9300	0.000005002	0.000005372	0.000009650
resume_subscription	3	1723	1723	1723	0.000005000	0.000005068	0.000005861
revoke_delegation	19	255	519	353	0.000005000	0.000005014	0.000005176
subscribe	32	6485	14009	7663	0.000005002	0.000005306	0.000008831
transfer_fixed	9	5476	11466	7864	0.000005002	0.000005314	0.000008932
transfer_recurring	19	5591	16091	7303	0.000005002	0.000005292	0.000008651
transfer_subscription	10	5838	13431	7943	0.000005002	0.000005317	0.000008971
update_plan	22	424	503	477	0.000005000	0.000005019	0.000005238

Generated: 2026-06-02