docs: bounded parallel Actions within one Mission (NO_BUMP)

[pcvantol]

Owner-requested architectural refinement

The owner requested that independent Engineering Actions within one Forge Mission can be planned and executed concurrently by EP, rather than inheriting the current serial _OneActionProvider/single-target runtime limit. This is the next bounded documentation update in the existing protected design-delivery workflow, not an implementation or runtime instruction.

Changes

• Refine the existing Living Mission Graph design rather than introduce another planner.
• Update the canonical Forge roadmap and its implementation DAG.
• Add the detailed parallel-runtime contract, seven PLANNED Forge nodes and a non-executable JSON DAG.
• Add 26 shared future qualification families covering actual EP execution overlap, per-target Truth/state, scoped credentials, bounded fan-out, partial submission, restart/CAS, incremental fan-in, joins, cancellation/completion and timing/usage.
• Clarify that A-only successors can advance while B runs; no artificial wave barrier and no equation of subagents with Actions.

EP companion branch: codex/parallel-action-execution-v1-design (six owning nodes). Workspace/full fleet/native subagents are not new prerequisites. Serial Mission 3 and the active reset work stay unchanged. No code, package/version, workflow, policy/grant, credential, database, installation, Mission or paid provider execution changes.

Validation at creation

Exact-head CI and author-side documentary/DAG review pending. No local full product-suite or installed concurrency qualification claimed. Merge must respect actual repository-required checks/reviews and the exact reviewed head; no protection bypass or fabricated independent assurance.

[pcvantol]

Author-side documentary review for head 60433c152d1e03a24c84f6cb0a6ec0ef8a41b85a, coordinated with EP #274 at 0095c4e5c8033c3a547a328fdcb8a614794bd01b:

• Inspected the canonical-roadmap patch: only the second cross-repository milestone is strengthened, linked to PA design/roadmap, and its parallel result/closure expectations refined. No unrelated historical programme entries or serial-canary criteria changed.
• Locally parsed both exact documentary DAG payloads and matched their Git blob hashes to remote: Forge 0d511446414ac81f1d75939dfed5b7d0059b20bf; EP 02ae60374a95d8a9f55800b774dde00bd6608992.
• All 13 nodes and 20 combined dependency edges resolve; both local graphs and the combined graph are acyclic. All nodes are PLANNED, executable=false, current_mission_3_dependency=false. No Workspace prerequisite or Forge-final/EP-final qualification cycle.
• Reviewed per-Action target/scope, immutable submissions, short CAS transactions, in-flight contribution reservations, incremental A-only successors, genuine multi-parent artifact joins, cancellation/uncertain-effect completion barrier and Action-vs-subagent distinctions.
• PA-01..PA-26 are future qualification obligations, NOT an executed concurrency test suite. This is author-side design review and structural validation, not fabricated independent Quality/Security assurance. Runtime behavior, policies, credentials, production data and the active reset implementation were not changed.

Exact-head repository CI is still pending; protected delivery must wait for its actual required result.