Follow-up: scan full Dependencies section for Blocked by extraction

[RyaanLari]

Motivation

• The existing parser used readSection, which collapses a markdown section to its first non-empty line, so Blocked by: lines appearing later in the Dependencies (Blocked By / Blocks) section were missed.
• The change ensures project-field synchronization continues to work when Blocked by: appears anywhere inside the Dependencies block rather than only at the top.

Description

• Added readSectionBlock(body, heading) to return the full section body (and ignore the GitHub sentinel) instead of just the first non-empty line.
• Updated readBlockedByFromDependencies to use readSectionBlock(...) and iterate all lines in the Dependencies section.
• Broadened the Blocked by matcher to accept optional markdown list markers (for example, - Blocked by: ...) to handle common template formatting.

Testing

• Inspected the updated workflow portion with nl -ba .github/workflows/projects-field-sync.yml | sed -n '110,190p' and verified the new helper and updated usage are present (succeeded).
• Ran rg -n "readSection\\(|readBlockedByFromDependencies|Blocked by" .github/workflows/projects-field-sync.yml to confirm references were updated (succeeded).

---

Codex Task