v1.0 readiness checklist — converge on production-grade stability

[JerrettDavis]

Problem:
We're approaching v1.0, but several design, testing, and documentation gaps remain. A clear checklist ensures we ship a solid, maintainable release.

Motivation:
v1.0 signals API/config stability, production readiness, and a commitment to semantic versioning. A public checklist builds confidence with enterprise adopters.

Proposed Approach & Acceptance Criteria:
This meta-issue tracks completion of v1.0 readiness. v1.0 ships ONLY when all Required items below are complete (green):

REQUIRED FOR v1.0:

• Design-time build guard (in flight) — PR to detect when JD.Efcpt.Build runs in design-time context and skip generation to prevent IDE hangs
• Compatibility matrix CI (in flight) — GitHub Actions matrix: .NET 8/9/10 × SQL Server/PostgreSQL/MySQL/Oracle/Snowflake/Firebird/Sqlite × Windows/Linux/macOS
• API & property-name stability review — audit RunEfcpt.cs public API, efcpt-config.json schema; lock in stable names
• Documentation completeness pass — ensure docs/user-guide, docs/architecture, samples cover all providers and common scenarios
• Sample project per provider — one reference sample (.csproj + config + output) for each of 7 supported providers
• Cache SDK probe — Cache dnx/SDK capability probe to reduce build overhead #187 (eliminate per-project redundant probes in multi-project builds)
• Streamlined .NET 8/9 tool acquisition — Automatic tool acquisition fallback for .NET 8/9 #186 (automatic fallback, no manual setup friction)
• Offline mode — Add offline mode for air-gapped and secure CI environments #185 (air-gapped enterprise CI support)
• awesome-dotnet/awesome-efcore listing — submit JD.Efcpt.Build for visibility

POST-v1.0 ROADMAP (tracked, not blocking v1.0):

• Companion dotnet tool — Add companion dotnet tool for project initialization and diagnostics #181 (jd-efcpt init, doctor diagnostics)
• Visual Studio extension — Add Visual Studio extension for build-time UI and on-demand regeneration #182 (build-time UI, regen on-demand)
• VS Code extension — Add VS Code extension for C# Dev Kit users #183 (C# Dev Kit integration)
• Provider plugin registry — Open provider detection to a plugin/registry model #184 (third-party provider support)
• Secret-manager sourcing — Add pluggable connection string sourcing (Key Vault, Secrets Manager, env vars) #188 (Key Vault, Secrets Manager, env vars)
• Split provider drivers — Lazy-load or split ADO.NET provider drivers to reduce package weight #189 (reduce package weight)
• Worktree test compatibility — Test suite fails when run from a git worktree — FindRepoRoot() assumes .git is a directory #190 (git worktree support for contributor workflows)

Related PRs: design-time guard and compat matrix CI in flight.