Bound runner prompts with explicit required task input reads

Changes: Keep startup instructions and exact context packets inline while listing supplementary task inputs as mandatory project reads. Preserve root containment, missing-artifact guidance and budget failures. Add S21-006 exact UI context regression and cover claim/review budgets for all tasks; leave stdin delivery unchanged.
Validation: make check passed all 68 tests, including delayed UTF-8 stdin/EOF, timeout and terminal-transition checks. All 556 current prompts fit 80000 characters; largest 77693. git diff --check passed. Foundation checks do not establish application readiness.