fix(taskctl): concurrent task limit regressed from 10 to 5 after merge

[randomm]

Bug

The maximum concurrent task limit in the task pipeline has regressed from 10 to 5, likely introduced during a recent merge.

Expected Behavior

Up to 10 tasks should be able to run concurrently in the pipeline (as documented in AGENTS.md and the PM orchestration system).

Actual Behavior

The system caps at 5 concurrent tasks, blocking further dispatch even when capacity should be available.

Investigation Needed

• Locate where the concurrency cap is defined (likely packages/opencode/src/tasks/pulse.ts or a related config constant)
• Identify the commit that introduced the regression
• Restore the limit to 10

Acceptance Criteria

• Concurrent task limit restored to 10
• Regression test or constant clearly named to prevent future silent changes
• .fork-features/manifest.json updated to track this as a fork feature
• bun run typecheck — 0 errors
• bun test — 0 failures
• Adversarial review: APPROVED

Quality Gates

• bun run typecheck — 0 errors
• bun test — 0 failures