ci: use shared cargo publish action

[dev-jodee]

Summary

• Replace inline Rust client publishing logic with the shared cargo-publish action.
• Keep repo-specific release tests, client generation, tags, GitHub releases, and summaries in this workflow.
• Use skip-existing and action outputs so reruns are recoverable when the crate version already exists.

Test Plan

• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/publish-rust.yml"); puts "ok"'\n- git diff --check\n- cargo metadata --locked --no-deps --format-version 1\n- Dry-run publish workflow passed: https://github.com/solana-program/subscriptions/actions/runs/26239417315\n\n## Dependency\n- Depends on feat: add cargo publish action solana-developers/github-actions#15 merging first, because this workflow references solana-developers/github-actions/cargo-publish@main.

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Project	Deployment	Actions	Updated (UTC)
solana-subscriptions-program	Ready	Preview, Comment	May 22, 2026 12:56pm

[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	7	1803	1833	1807	0.000005000	0.000005072	0.000005903
create_fixed_delegation	38	3514	9542	4921	0.000005001	0.000005196	0.000007460
create_plan	96	3436	15436	4876	0.000005001	0.000005195	0.000007438
create_recurring_delegation	27	3533	11038	5151	0.000005001	0.000005206	0.000007575
delete_plan	9	359	359	359	0.000005000	0.000005014	0.000005179
init_subscription_authority	153	6226	26496	9089	0.000005002	0.000005363	0.000009544
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	6473	13973	7557	0.000005002	0.000005302	0.000008778
transfer_fixed	6	5208	6711	5460	0.000005001	0.000005218	0.000007730
transfer_recurring	17	5323	11323	6678	0.000005002	0.000005267	0.000008339
transfer_subscription	10	5533	11572	6627	0.000005001	0.000005265	0.000008313
update_plan	22	424	503	477	0.000005000	0.000005019	0.000005238

Generated: 2026-05-22