chore(board): drop the Ready to push status from board-snapshot

[wstein]

Drops the Status option "Ready to push" from scripts/board-snapshot.sh, its tests and docs/content/docs/manual/board-tooling.md, after the code stopped using forge.StatusReadyToPush (#514, PR #516). The required Status options are now Todo, In progress, Blocked, In review and Done. A board that still has the legacy option keeps it and its option ID (configure adds it back so the compatibility check passes; it never deletes or renames options), sync leaves a card in that status alone and move refuses it as an unknown status. The "Release and milestones" view filter, which depended on the status clause and had been reported invalid, now selects all open issues in the repository, as the issue asks. The "Ready to push?" Decision card is untouched.

Closes #515

🤖 Generated with Claude Code

[wstein]

Review evidence (Opus 5.5, independent reviewer, exact head 79e7669, directly on main ffe9c22; scripts/ is a security-relevant path):

• CLEAR, no Medium or High findings. Verified in the script: the required Status options are exactly Todo, In progress, Blocked, In review, Done; a legacy "Ready to push" option is kept with its option ID (configure refuses unknown options, never deletes or renames them, and writes nothing when the names already match); sync leaves a legacy card alone; move refuses the status. No new write path, no gh project item-edit, no extra GraphQL calls, token handling untouched. The view filter change is in scope (the issue asks for it; the old filter depended on the status clause).
• A mutation check: deleting the new legacy line makes TestBoardSnapshotConfigureToleratesLegacyReadyToPush fail, so the test guards the regression.
• go test ./scripts/ exit 0 (full run), gofmt -l scripts empty, make check-ci exit 0, make commitlint exit 0. No design page changed, no overlap with PR docs(design): drop the Ready to push board status from D30 #519. AGENTS.md unchanged.
• Not verified: the script against the real GitHub board and the view filter there (fake gh only); applying it is the human's step.
• Lows (batched on Batched Lows from the #391 to #396 reviews #399): the new test could assert that the Status option IDs survive and that no Status field update is issued; it duplicates a rewrite loop of sessionSchemaFixture; uneven line wrapping in board-tooling.md.

[wstein]

Re-stamp after the rebase onto main 693ae56 (#519 and #520 merged): Opus 5.5 narrowed re-review CLEAR on the exact head 9cfdb97 (earlier CLEAR on 79e7669). git range-diff ffe9c224..79e7669b origin/main..9cfdb973 shows =; no file is shared between the main change and the branch; nothing under docs/content/docs/design/* or docs/releases/* is touched. go test ./scripts/ exit 0, gofmt -l scripts empty, make check-ci exit 0, make commitlint exit 0 on the exact SHA; the message is unchanged.