[CI] Version both baseline files and split conformance badges per spec (#459)

- Rename conformance-baseline.yml to conformance-baseline-2025-11-25.yml
  so both baseline files carry their spec revision symmetrically, and
  bring conformance-server/conformance-client up to the same rigor
  (--suite all, pinned CONFORMANCE, baseline check) as the draft targets
- score.php now takes a required spec-version and writes
  <suite>-conformance-<spec-version>.json, so 2025-11-25 and 2026-07-28
  each get their own badge instead of only the dated one
- conformance-weekly.yaml generates and publishes badges for both
  matrix entries instead of gating on 2025-11-25 only, and drops the
  now-stale unversioned badge files from the badges branch
- README shows all four badges alongside the existing packagist/CI/PHP
  version/license row
- Trimmed workflow comments to the minimum needed

tests/Conformance/conformance-baseline.yml

@@ -1,38 +0,0 @@
-# Both pre-existing fixture bugs, not lifecycle-specific: json-schema-2020-12
-# wants a `json_schema_2020_12_tool` fixture neither conformance server
-# defines, and resources-templates-read emits a resource-template URI in a
-# shape the schema rejects. Reproduce identically on the 2026-07-28 endpoint
-# (see conformance-baseline-2026-07-28.yml).
-server:
-  - json-schema-2020-12:json-schema-2020-12-tool-found
-  - resources-templates-read:wire-schema-valid
-
-client:
-  - elicitation-sep1034-client-defaults
-  - sse-retry
-  # The example client doesn't call add_numbers or echo the tool's inputSchema
-  # back, so these checks have nothing to exercise.
-  - tools_call:tool-add-numbers
-  - json-schema-2020-12-preservation:json-schema-2020-12-client-echo-completed
-  - auth/metadata-default
-  - auth/metadata-var1
-  - auth/metadata-var2
-  - auth/metadata-var3
-  - auth/basic-cimd
-  - auth/scope-from-www-authenticate
-  - auth/scope-from-scopes-supported
-  - auth/scope-omitted-when-undefined
-  - auth/scope-step-up
-  - auth/scope-retry-limit
-  - auth/token-endpoint-auth-basic
-  - auth/token-endpoint-auth-post
-  - auth/token-endpoint-auth-none
-  - auth/pre-registration
-  - auth/2025-03-26-oauth-metadata-backcompat
-  - auth/2025-03-26-oauth-endpoint-fallback
-  - auth/offline-access-scope
-  - auth/offline-access-not-supported
-  - auth/client-credentials-jwt
-  - auth/client-credentials-basic
-  - auth/cross-app-access-complete-flow
-