v0.9.14 — accessibility conformance + axe gate

Accessibility conformance, and the scanner that keeps it true
(m9-a11y-fixes, owner-approved same day).

Added

• Accessibility gate: the e2e harness now runs the axe-core WCAG 2.1 A/AA
  ruleset across 14 core screens and fails on any serious or critical
  violation (FRG-PROC-019). The harness is fully green — 36 scenarios, the
  a11y tier included.

Fixed

• All four serious accessibility violations found by the post-cycle scan
  (FRG-UI-038): the connection indicator is now screen-reader-perceivable;
  muted text and danger-toned text meet the 4.5:1 contrast minimum everywhere
  (new --color-danger-text tone); indexer/download-client cards no longer
  nest interactive controls (the provider name is the keyboard edit control);
  the Health components table is keyboard-scrollable. Verified: a full axe
  sweep of all 21 screens reports zero violations.
• The e2e harness's stale expectations (pre-existing red): renaming is pinned
  on in the harness and expectations follow the current naming template;
  the Sources spec no longer pins the pre-extension "Coming soon" chip.

No behavior changes; no upgrade steps.