feat: migrate to v1.0.0 for package manager compliance (atomic Go module migration)

[vxfemboy]

⚠️ Why This PR Exceeds the 5-File Limit

I understand the preference for PRs with ≤5 files modified. However, this Go module path migration must be atomic to prevent CI failures and build breakage.

Technical Constraint: Go Module Migration Must Be Atomic

When changing a Go module path in go.mod, all import statements across the entire codebase must be updated simultaneously in the same commit/PR. Here's why:

// In go.mod
module github.com/vmfunc/sif  // ← If we change this...

// Then ALL of these break immediately:
import "github.com/dropalldatabases/sif/internal/config"  // ❌ Won't compile
import "github.com/dropalldatabases/sif/internal/scan"    // ❌ Won't compile

If split into multiple PRs:

1. PR Base scanning doesn't occur even when --noscan is present #1 changes go.mod → All subsequent PRs fail CI (can't import old path)
2. PR 🎀 feat: Shodan Integration #2 tries to fix imports → Can't merge until PR Base scanning doesn't occur even when --noscan is present #1 merges (circular dependency)
3. Main branch is broken between merges
4. All CI checks fail until every PR merges

The only working approach: Change go.mod + all imports in a single atomic PR.

What We're Doing About the File Count

To minimize impact, we're splitting independent changes into separate PRs:

• ✅ Can be separate PR: Domain fixes (remove references to lunchcat domain #50) - Makefile, .all-contributorsrc, README.md contributor links
• ✅ Can be separate PR: Discord link standardization - CONTRIBUTING.md, docs/README.md
• ⚠️ MUST be atomic: Module path migration - 36+ files (this PR)

This PR only contains the atomic Go module migration that cannot be split without breaking the build.

[vxfemboy]

[vmfunc]

blocked by #63, #64 and #62