[P1][Tier 1] Document end-to-end dev recipes for recurring change types

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Tier 1 — Foundation readiness · Priority: P1

Gap

Some recurring changes are covered by skills (adding-brokered-service, extension-development-host, running-integration-tests), but there is no consolidated set of step-by-step recipes for the FC's common change types showing where to add code, how to wire it in, and how to test it (e.g. add a command, add a setting, add a native AOT addon method, add an integration test scenario).

Investment

• Document recipes for the top recurring change types, each linking to the relevant skill and test command.

Acceptance criteria

• Recipes exist for the FC's most common change types.
• Each recipe shows add → wire → test and links to an existing skill where one exists.

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Part of epic #3273

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PR opened: PR 760007 (vs-green, target main). Adds the dev-recipes skill with add → wire → test recipes for the recurring change types, plus an "Adding a new recipe (for agents)" section. Rebased on merged main and reviewed by the code-review agent (two path/mechanic inaccuracies it found were fixed).

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✅ Done — implemented and merged.

PR: Merged PR 760007 — Add dev-recipes skill (vs-green, merged to main as 1eaf906).

What shipped: a dev-recipes skill — an intent-triggered index of the repo's recurring change types. It owns full add → wire → test steps for the changes with no other owner (add a command, add a setting) and points to the existing owner for the rest (native addon → native.instructions.md; integration test scenario → tests.instructions.md; brokered service → adding-brokered-service skill), so steps can't drift. Includes an "Adding a new recipe (for agents)" section so the recipe set compounds (prior art for the correct-once loop in #3291).

Acceptance criteria:

• Recipes exist for the FC's most common change types.
• Each recipe shows add → wire → test and links to an existing skill where one exists.

Reviewed twice by the code-review agent against the path-accuracy/no-duplication bar from PR 759084's review; all findings fixed.