fix(a11y): add aria-label to operations filter input

[yogeshwaran-c]

Description

The operations filter input (rendered when filter=true) only had a
placeholder attribute. Browsers and assistive technologies do not
expose placeholder as the accessible name of an input — once the user
types, the placeholder disappears entirely, and screen readers announce
the field as an unlabeled text box. This violates WCAG 2.1 success
criteria 4.1.2 (Name, Role, Value) and 1.3.1 (Info and Relationships).

This PR adds aria-label="Filter by tag" to the input so it has a
stable accessible name regardless of whether a value is present. The
visible placeholder is preserved so sighted-user UX is unchanged.

Motivation and Context

placeholder is widely flagged by automated and manual a11y audits
(axe, WAVE, Lighthouse) as not satisfying the "accessible name"
requirement. Inputs without an accessible name are a long-standing pain
point for users of screen readers and voice-control software.

How Has This Been Tested?

• New Jest unit test: test/unit/components/filter.jsx asserts the
  rendered input carries aria-label="Filter by tag".
• New Cypress e2e spec: test/e2e-cypress/e2e/a11y/filter-input.cy.js
  visits a real spec with filter=true and asserts both aria-label
  and the original placeholder are present on the live DOM input.
• Existing regression spec test/e2e-cypress/e2e/bugs/6276.cy.js
  continues to pass.

PASS test/unit/components/filter.jsx
  <FilterContainer/>
    √ renders FilterContainer if filter is provided
    √ does not render FilterContainer if filter is false
    √ exposes an accessible name on the filter input via aria-label

✔  filter-input.cy.js   2 passing
✔  6276.cy.js           3 passing

Screenshots (if appropriate):

N/A — DOM-only change. The input renders identically; only the
accessibility tree gains a name.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.