docs(roadmap): add Planning Approach page

- New planning_approach.rst summarising how v1.0 is planned: GitHub project,
  Product Increment tickets per Feature Team / Community mapped to milestones,
  sub-tickets and the GitHub project's process area attribute for grouping.
- Link to the authoritative Platform Management Plan as primary reference.
- Add the page to the roadmap toctree (after Overall Status).

Author: antonkri

docs/s_core_v_1/roadmap/planning_approach.rst

@@ -0,0 +1,81 @@
+..
+   # *******************************************************************************
+   # Copyright (c) 2026 Contributors to the Eclipse Foundation
+   #
+   # See the NOTICE file(s) distributed with this work for additional
+   # information regarding copyright ownership.
+   #
+   # This program and the accompanying materials are made available under the
+   # terms of the Apache License Version 2.0 which is available at
+   # https://www.apache.org/licenses/LICENSE-2.0
+   #
+   # SPDX-License-Identifier: Apache-2.0
+   # *******************************************************************************
+
+:hide-toc:
+
+.. _v1_0_planning_approach:
+
+Planning Approach
+=================
+
+.. note::
+
+   This page is **a short summary** of how the S-CORE v1.0 roadmap is
+   planned. The authoritative planning procedure — covering project
+   management, release management, change management and the underlying
+   governance — is described in the
+   `Platform Management Plan
+   <https://eclipse-score.github.io/score/main/platform_management_plan/index.html>`__
+   (in particular
+   `Project Management
+   <https://eclipse-score.github.io/score/main/platform_management_plan/project_management.html>`__
+   and
+   `Release Management
+   <https://eclipse-score.github.io/score/main/platform_management_plan/release_management.html>`__).
+
+Where we plan
+-------------
+
+All v1.0 planning is tracked in the central GitHub project
+`S-CORE v1.0 Planning <https://github.com/orgs/eclipse-score/projects/17/views/37>`__.
+This project is the single source of truth for the roadmap; the figures and
+tables shown elsewhere in this section are derived from it.
+
+Product Increments per Feature Team / Community
+-----------------------------------------------
+
+Every Feature Team and every Community creates **one ticket of type
+"Product Increment"** for each release gate they contribute to. This ticket:
+
+- is the **main ticket** for the team's work in that release gate,
+- is **mapped to the corresponding milestone** (using the ticket's
+  *milestone* attribute) in the
+  `eclipse-score/score milestones
+  <https://github.com/eclipse-score/score/milestones>`__ (e.g. ``v0.8``,
+  ``v0.9``, ``v0.10``, ``v1.0``), and
+- represents the team's commitment for that release gate.
+
+Sub-tickets — the actual work
+-----------------------------
+
+All work the team performs for the corresponding milestone / release gate is
+**linked as sub-tickets under the Product Increment ticket**.
+
+- The breakdown does **not need to be exhaustive**; it can be detailed if a
+  team wants to, but at a minimum it should reflect the **main achievements
+  or work packages** planned for that release gate.
+- The sub-ticket structure ensures that the Product Increment ticket gives a
+  meaningful overview of the team's scope without having to dig through every
+  individual issue.
+
+Process-area attribute
+----------------------
+
+Wherever possible, each sub-ticket sets the **process area** GitHub project's
+attribute, for
+example ``pa1_req_eng``, ``pa2_arch_design``, ``pa3_implementation``,
+``pa4_verification``. This makes it possible to group and filter tickets not
+only **by time** (milestone / release gate) but also **by function**
+(process area), which is what feeds the per-process-area views on the
+:doc:`Overall Status <overall_status>` page.

docs/s_core_v_1/roadmap/roadmap.rst

@@ -194,6 +194,7 @@ Status & Next Steps
    :maxdepth: 1
 
    Overall Status <overall_status>
+   Planning Approach <planning_approach>
    Release Gate v0.8 — Requirements Engineering + Architecture Design <pi1>
    Release Gate v0.9 — Implementation <pi2>
    Release Gate v0.10 — Verification <pi3>