Refactor provider-resources skill into SDK-specific guidance skills

[bbasata]

Replace the single mixed-SDK provider-resources skill with three focused skills:

• provider-resources: now a categorizer that reads go.mod to detect whether
  the provider uses terraform-plugin-mux (combined), terraform-plugin-framework
  (Framework-only), or neither (SDKv2-only), then routes to the appropriate skill
• provider-development-with-framework: Framework-only implementation guide
  (CRUD, schema, plan modifiers, validators, state management, testing)
• provider-development-with-sdk: SDKv2-only implementation guide
  (CRUD, schema, ForceNew, timeouts, tfawserr error handling, testing)

Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com

[github-actions]

Tessl Skill Review Results

Skill	Status	Review Score
terraform/provider-development/skills/provider-resources	PASSED	95%
terraform/provider-development/skills/provider-resources-with-framework	PASSED	77%
terraform/provider-development/skills/provider-resources-with-sdk	PASSED	84%

Checks: frontmatter validity, required fields, body structure, examples, line count.
Review Score is informational — not used for pass/fail gating.

[AdamTylerLynch]

Duplicate/overlap flag: #79 also rewrites this same file, terraform/provider-development/skills/provider-resources/SKILL.md, with a different design, so the two PRs will conflict on merge:

• This PR (Refactor provider-resources skill into SDK-specific guidance skills #41): splits provider-resources into a router + provider-resources-with-framework / provider-resources-with-sdk.
• provider-resources: replace AWS-internal patterns with generic Plugin Framework guidance #79: keeps provider-resources as one Framework-first skill and removes the terraform-provider-aws-internal patterns it was implicitly written against (conns.Client, tftags, verify.SetTagsDiff, ProtoV5, legacy website/docs/).

Both address the split-vs-single discussion in #14. Raising this so the two can be reconciled instead of one silently overwriting the other. Related: my #86 (provider-framework-migration) houses the SDKv2→Framework content separately, which is one way to keep this skill Framework-only without an SDK sibling.

[leefowlercu]

Thank you for this proposal, @bbasata. The implementation merged in #90 adopted the Plugin Framework-first provider resource guidance from #79 together with the SDKv2-to-Plugin Framework migration guidance from #86, superseding the SDK-specific Skill split proposed here. Closing this pull request as superseded by #90.