docs(openspec): sync quoted-free-text pattern rule into tool-approval-gates (#1406)

[Aaronontheweb]

What

Reconcile the tool-approval-gates spec with the behavior that PR #1815
merged for issue #1406. This is the OpenSpec follow-up to that fix.

Changes

• Add the quoted-free-text termination rule to the "Shell command pattern
  matching" requirement in openspec/specs/tool-approval-gates/spec.md. The
  rule sits next to the digit-bearing rule (Verb chain extraction includes bare integer positional arguments, creating overly-specific approval patterns #1331) and the multi-line rule
  (Multi-line quoted strings break shell approval prompt rendering and stored patterns #1402). A quoted argument with internal whitespace is call-specific free
  text and stops pattern extraction.
• Pin the shipped constraints with four scenarios:
  • a multi-word quoted operand drops from the pattern (git commit -m "fix the bug" -> git commit -m)
  • multi-word quoted operands generalize across values
  • a single-word quoted argument stays in the pattern
  • a quoted path keeps directory scoping
• Archive the completed change under openspec/changes/archive/.

Notes

• Spec only. The code already merged in PR fix(approvals): drop quoted free-text operands from stored approval patterns (#1406) #1815 (commit 4836e88).
• The rule normalizes the stored and display pattern. It does not change the
  live authorization decision. The PR fix(approvals): drop quoted free-text operands from stored approval patterns (#1406) #1815 adversarial review confirmed this.
• openspec validate passes for tool-approval-gates. The pre-existing
  netclaw-tools validation failure is unrelated to this change.