refactor(framework): replace skill test sections with scoped rules #985

Problem

Dedicated Test sections scatter constraints that already belong to an action's process or the skill's shared rules. The skill generator also requires a test table per action, encouraging this duplication.

Skills should read as a logical sequence of actions, supported by rules at the appropriate scope. Some existing test entries carry useful verification or stopping conditions; preserve those requirements during the migration.

Scope

• Remove dedicated Test / Tests sections from all shipped skill definitions, including routers and actions.
• Use one skill-level Rules section for constraints that apply to the whole skill and all its actions.
  • Consolidate existing Transversal rules into it, without adding a parallel section.
• Allow an optional action-level Rules section for constraints that apply to the entire action, only when the action owns them.
  • Keep shared constraints at their owning source rather than repeating them in every action.
• Keep ordered execution, concrete verification steps, and branching or stopping behavior in the process.
• Review each removed test entry: merge duplicates, relocate invariants to their owning rules, and turn necessary checks into executable process steps.
• Update the skill generator's authoring contract, planning and writing actions, templates, and review guidance to produce this structure.
  • Replace R11's test-section requirement and R13's mandatory test table with the rules-scope contract.
• Update affected documentation, validation fixtures, snapshots, and checks that depend on the old structure.

Acceptance criteria

• All shipped skill routers and actions use the new structure without dedicated Test / Tests sections.
• Skill-level rules apply across all actions; action-level rules apply only within their owning action.
• No shared rule is duplicated across action files, and no parallel Rules / Transversal rules sections remain.
• Every meaningful invariant, verification step, failure condition, and stopping condition from the removed sections has an appropriate home.
• Processes remain a logical sequence of actions; the migration is not a mechanical renaming of test tables to rules.
• Creating and modifying a skill through the generator produces the new structure.
• Repository checks pass with affected fixtures and snapshots updated.

Prior art in this repo

• Skill authoring contract: R11 defines action sections; R13 requires observable test tables; R9 and R17 establish rule ownership.
• Action template and router template: the current generated structure.
• Skill planning and skill writing: per-action tests are planned and copied into generated actions.
• Commit action: an example of useful verification conditions to preserve.
• Related PR #981: readability, conflict checking, and references by purpose.

Out of scope

• Removing developer test suites, acceptance criteria in product or implementation artifacts, or the actual testing and QA capabilities of skills.
• Changing action outcomes or weakening required verification and approval gates.