Allow dynamic environment names (if/else approach)

[fabn]

Summary

• Add regex pattern support to environment_targets input (e.g., "production,dev-.*,staging")
• When a pattern like dev-.* matches user input dev-feature-1234, the resolved environment name is the actual user input, not the pattern
• Invalid regex patterns fall back to exact string matching (no crash)
• Implementation uses targetMatch() helper with all existing if/else comparison branches updated

Note: This is the "if/else" approach. See #2 for the alternative pattern-table approach.

Closes github#320

Test plan

• All 427 existing tests pass
• 14 new tests covering regex patterns, "to" syntax, noop, stable branch, params, lock/unlock, anchoring, invalid regex fallback
• Manual test with environment_targets: "production,dev-.*" and .deploy to dev-anything

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