test(telemetry): add comprehensive unit tests for telemetry_cmd.rs (fixes #1254)

[jlaportebot]

Fixes #1254

Changes

• Added comprehensive unit tests for (~165 lines) covering all major functions
• Tests cover with various HTTP responses, headers, and edge cases
• Tests cover behavior including salt deletion, hash preservation, marker file, history.db cleanup
• Tests cover consent/enabled string mappings, env override detection, consent date
• Tests cover config updates and field preservation
• Tests cover terminal requirement and input validation (y/yes variants)
• Tests cover decision logic (consent, enabled, env, URL, marker timing)
• Tests cover early returns for consent=true/false and non-TTY

Testing

• All 35 new tests in pass
• All 26 existing telemetry tests in and pass
• Full test suite passes (2280+ tests)
• passes
• passes (zero warnings)
• CI will run on all targets

AI Disclosure

This PR was created with AI assistance (Hermes Agent).

[jlaportebot]

All CI checks pass (CLA check green). PR is mergeable with no conflicts. Awaiting maintainer review/merge (blocked by merge queue policy).

[jlaportebot]

Closing as duplicate of #2880 (same issue #1254). Consolidating work into the newer PR.