ci: pass deployer pubkey as buffer authority for devnet

[dev-jodee]

Summary

• Derive the deployer pubkey from the materialized keypair and pass it as buffer-authority-address for devnet releases.
• Unblocks Write program buffer on devnet, which was retrying 50× then failing.

Root Cause

solana-developers/github-actions/write-program-buffer runs an internal Transfer buffer authority step whenever steps.check-program.outputs.exists == 'true':

solana program set-buffer-authority $BUFFER \
  --keypair ./deploy-keypair.json \
  --new-buffer-authority ${{ inputs.buffer-authority-address }} \
  --url ${{ inputs.rpc-url }}

We were passing an empty buffer-authority-address on devnet, so the CLI rejected the call:

error: The argument '--new-buffer-authority <NEW_BUFFER_AUTHORITY>' requires a value but none was supplied

The action has no flag to skip this step, so we satisfy it by transferring authority to the deployer itself (effective no-op).

Test Plan

• Trigger Release workflow against devnet from this branch.
• Confirm Write program buffer succeeds (including the Transfer buffer authority sub-step).
• Confirm Upgrade program (devnet) proceeds and the program upgrade lands.

Failing run for reference: https://github.com/solana-program/subscriptions/actions/runs/25179831115

[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	11	1805	2118	2003	0.000005000	0.000005080	0.000006001
close_subscription_authority	7	1881	1916	1886	0.000005000	0.000005075	0.000005943
create_fixed_delegation	38	3621	18030	5466	0.000005001	0.000005218	0.000007733
create_plan	84	3540	13450	4757	0.000005001	0.000005190	0.000007378
create_recurring_delegation	27	3640	12645	5369	0.000005001	0.000005214	0.000007684
delete_plan	8	416	416	416	0.000005000	0.000005016	0.000005208
init_subscription_authority	142	8931	25851	12068	0.000005003	0.000005482	0.000011034
revoke_delegation	19	318	585	420	0.000005000	0.000005016	0.000005210
subscribe	21	6666	9690	7462	0.000005002	0.000005298	0.000008731
transfer_fixed	6	10102	13105	11354	0.000005003	0.000005454	0.000010677
transfer_recurring	17	10212	13299	11484	0.000005003	0.000005459	0.000010742
transfer_subscription	10	10495	20995	12150	0.000005003	0.000005486	0.000011075
update_plan	21	424	500	474	0.000005000	0.000005018	0.000005237

Generated: 2026-04-30