fix: address Copilot review round 5 on #2251

Two of these reverse round 4, which asked for the opposite. Where the
readings conflict I took the permissive one: a wrong tightening rejects
conforming servers, a wrong loosening only fails to report something.

- skills.ts: stop requiring the `skill:` scheme. SEP-2640 says a server
  SHOULD use `skill://` and explicitly allows a domain-native scheme, so
  round 4's requirement handed a conforming `github://…` skill a false
  `malformed-uri` and skipped its name and root checks. Containment is
  scheme-independent — it compares against THIS entry's own root — so the
  traversal fix that requirement came packaged with is unaffected.
- skills.ts: the 512-entry and 16 MiB limits are warnings. Both are
  SHOULD NOTs for a server and MAYs for a host, so calling them errors
  contradicted the "error = a MUST was broken" contract round 4
  established and told authors a permitted skill was invalid.
- skills.ts: `skillEntriesMatch` compares canonically — keys sorted,
  manifest sorted by URI. `JSON.stringify` treated key order and manifest
  order as differences, though neither carries meaning.
- SkillsScreen: a differing `skills/get` is "a different snapshot"
  (yellow), not a disagreement (red). The SEP defines it as a fresh
  point-in-time read, so a skill that changed since the listing
  legitimately differs.
- useServerCommands: route `onGetSkill` through the command-scoped OAuth
  recovery like every other server command. An expired authorization
  rendered an error and stopped there — no reauthorization, no retry.
- test-servers/skills.ts: stamp the modern base result envelope
  (`resultType` / `ttlMs` / `cacheScope`) on every skills result. The SDK
  stamps it only for methods in its own codec, and `skills/*` are
  consumer-owned, so a 2026-era connection was receiving results without
  it. Unconditional rather than per era: the modern leg builds a server
  per request, so there is no era to branch on at registration time, and
  on legacy they are three members no codec inspects.
- composable-test-server: remove the `skills.directoryRead` option. It was
  publicly settable and advertised a method nothing serves, producing the
  exact false capability the fixture exists to help catch. `skills` is now
  a plain boolean; the flag returns in phase 3 (#2248) with its handler.

Still not changed: whether a modern `skills/list` RESULT SCHEMA must
require that envelope. Stamping it server-side is free; requiring it
client-side would reject servers on a reading nobody has checked against
the normative text. #2248 owns settling it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018kfrH3uRNUM4JAk1reKtyY
Signed-off-by: cliffhall <cliff@futurescale.com>

test-servers/configs/skills-http.json

@@ -3,9 +3,13 @@
     "name": "skills",
     "version": "1.0.0"
   },
-  "tools": [{ "preset": "echo" }],
+  "tools": [
+    {
+      "preset": "echo"
+    }
+  ],
   "resources": [],
-  "skills": {},
+  "skills": true,
   "transport": {
     "type": "streamable-http",
     "port": 3230