tests/interaction: annotate removed_in on entries whose spec section is gone in 2026-07-28

85 requirements whose source spec section is deleted in the 2026-07-28
revision now carry removed_in="2026-07-28" plus a one-line note citing
the SEP and whether there is a replacement:

- ping (SEP-2575, no replacement)
- logging/setLevel, notifications/roots/list_changed (SEP-2575)
- Mcp-Session-Id and protocol-level sessions: hosting:session:*,
  client-transport:http:session-*, flow:session:* (SEP-2567)
- standalone GET stream + Last-Event-ID resumability: hosting:resume:*,
  hosting:http:standalone-sse*, client-transport:http:reconnect-* (SEP-2575)
- resources/subscribe + unsubscribe (SEP-2575, replaced by
  subscriptions/listen)
- tasks/* (SEP-2663, moved to extension)
- -32042 URL-elicitation-required + elicitation/complete
  (SEP-2322 / spec PR #2891, replaced by MRTR input_required)

Inert today (SPEC_VERSIONS has only 2025-11-25); when 2026-07-28 is
added to the active axis these entries automatically drop their 2026
cells. No superseded_by links yet -- the 2026 replacement entries are
added with the implementation work.

test_coverage.py gains test_removed_entry_has_disposition: every
removed_in entry must carry note or superseded_by.

504 connect cells unchanged; 100% coverage; pyright/ruff clean.

Author: maxisbey