#28818 ci: warm-sources: cmux-tui's cargo jobs start from actions-cache

Follow-up to cmux#28572, now that the warm-sources table (cmux#28568) has landed on feat-cmux-next. cmux#28572 wired Swatinem/rust-cache into these jobs, so they move from their cold: … no warm source wired yet exemption to "warm": ["actions-cache"]:

• cmux-tui.yml msrv-check, optchat-chief, test-windows
• cmux-tui-sdks.yml rust-msrv

(cmux-tui.yml cdp-browser-smoke was already listed warm.)

tests/test_ci_warm_sources.py: these four entries pass check (c) (their steps wire actions-cache). The test's one failure is the same on feat-cmux-next without this change: cmux-tui-spec.yml acpmux-tests and fleet-test-compile.yml plan are not in the table yet (check (a)). That is not touched here.

Performance

No perf numbers: table bookkeeping only; the numbers are on cmux#28572.

Agent session: agent session

🤖 Generated with Claude Code

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Summary by cubic

Follow-up to cmux#28572: updates the warm-sources table so cmux-tui's cargo jobs list actions-cache as their warm source, matching the rust-cache wiring already in place.

• cmux-tui.yml msrv-check, optchat-chief, and test-windows, plus cmux-tui-sdks.yml rust-msrv, move from the cold exemption to "warm": ["actions-cache"].
• Table bookkeeping only; no perf numbers. The existing test failure for cmux-tui-spec.yml:acpmux-tests and fleet-test-compile.yml:plan is the same on feat-cmux-next and not addressed here.