Plan a deployment

Resolves immutable inputs and estimates effects without provider mutation or billable work. The plan targets Dev unless environment is prod; a Prod plan builds straight into Prod, except that a project with shared data and a database only reaches Prod through promotion. Managed mail requires a confirmed Paid service period; it is checked again before build reservation. Selecting the managed Better Auth bridge does not require managed mail or Paid access. An old sender configuration is not Paid authority. A commit the platform does not admit answers 409 with a nonretryable problem code; for framework_conversion_required, detail is a fixed catalog sentence that names the file, the rule and the required change whenever the refusal is typed.