fix(L1): require complete initial upgrade schedules

[jackchuma]

Summary

• reject non-empty initial schedule imports unless they contain exactly all 14 contract-backed upgrades through Denim
• enforce the same completeness check while parsing deployment configs and expose the expected upgrade count
• preflight direct SystemDeploy inputs before any broadcast can leave a partial deployment
• update schedule fixtures and the cross-implementation full-schedule golden with explicit zero entries for unscheduled upgrades

Test plan

• just test (1,212 passed, 1 skipped)
• just lint-check
• just snapshots

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1