docs(adr-022): mark Accepted, update env/compose/migration docs for LOGIN_FLOW rename

Follow-up to the LOGIN_FLOW rename. The user-facing surface area —
env.sample, docker-compose.yml mcp-login-flow profile, migration
guide, ADR statuses, and the running.md boot-log examples — all need
to refer to `login_flow` rather than the deprecated
`oauth_single_audience` string.

- docker-compose.yml: add explicit MCP_DEPLOYMENT_MODE=login_flow to
  the mcp-login-flow profile (no longer relying on auto-detection).
- env.sample: update the deployment-mode list and example, dropping
  the removed `oauth_token_exchange` and pointing at ADR-022 for the
  rename rationale.
- docs/ADR-022: flip Status to Accepted with a note that this PR
  implements step 1 (rename + validation gate).
- docs/ADR-021: note that it has been partly superseded by ADR-022
  (the oauth_single_audience naming is no longer accurate); cross-link.
- docs/ADR-025: drop oauth_single_audience/keycloak from the dynaconf
  validator example and the [oauth_single_audience] TOML section.
- docs/configuration-migration-v2.md: bulk-replace oauth_single_audience
  → login_flow throughout (sed -i).
- docs/running.md: re-collapse the per-mode boot-log subsections (added
  during the closed PR #786 workaround) back into a uniform
  "<mode>"-substitution block — now correct after this PR's logging
  cleanup at app.py:1172.

No code changes in this commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/ADR-022-deployment-mode-consolidation.md

@@ -1,7 +1,7 @@
 # ADR-022: Deployment Mode Consolidation via Login Flow v2
 
-**Status:** Proposed
-**Date:** 2026-02-01
+**Status:** Accepted (step 1 — `OAUTH_SINGLE_AUDIENCE` → `LOGIN_FLOW` rename + validation gate. Dead-code pruning is a follow-up.)
+**Date:** 2026-02-01 (accepted 2026-05-12)
 **Deciders:** Development Team
 **Related:** ADR-020 (Deployment Modes), ADR-021 (Configuration Consolidation), ADR-004 (Progressive Consent), Issue #521