fix(cli): require interactive purchase confirmation

[cristim]

Removes the --yes flag and its confirmation bypass. Both AWS purchase paths now require an affirmative terminal response once for the whole run; nonterminal stdin is refused even when it contains yes. Unattended dry runs retain their reports and audit records. Existing commands with --yes are rejected during parsing.

Closes #1943.

Validation: the flag regression fails on the original code and passes after the fix. The full race suite passed, followed by focused race checks after test-only review corrections. Build, vet, golangci-lint 2.10.1 and normal commit hooks passed. Local pseudo-terminal checks drove the actual prompt and both coordinators: yes/y produced two successful fake SDK purchases, no/EOF produced none, and removed-flag CLI invocations reached no provider. These were local fake-provider scenarios with synthetic credentials, not cloud purchases.

The terminal prompt is an operator safeguard, not a security boundary against software that can control a terminal.

Independent gpt-6-astra review approved commit 2c6f21a00cab38b21baa748326f15b686a140b1d after two source-review passes and final runtime verification in a separate clone. The reviewer independently passed focused race tests (7.436s), build, and all 16 local PTY/coordinator/CLI checks; restoring the original flag registration made the regression fail at the intended assertion. Required CI remains a merge gate. Local review substitutes for CodeRabbit under the session authorization.

[coderabbitai]

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Configuration used: Repository: LeanerCloud/cloud-commitments-cli/.coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 76d1d4e and 2c6f21a.

📒 Files selected for processing (10)

• README.md
• cmd/effective_dry_run_test.go
• cmd/helpers.go
• cmd/helpers_test.go
• cmd/main.go
• cmd/multi_service.go
• cmd/multi_service_test.go
• cmd/purchase_confirmation_test.go
• docs/cli/README.md
• docs/cli/purchase-safety.md

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