fix(mcp): correct the parked reason — the tokens work, the delivery does not

The previous note blamed infra#224 for cad and gitea-mcp being unreachable.
Both claims were wrong. infra#224 is closed, and closed deliberately: rather
than widening koala-homelab's grants, a second scoped token was provisioned at
~/.op-agent-write.env for AgentSecrets. Sourcing it makes `op vault list`
return AgentSecrets, and an MCP initialize against both endpoints returns 200 —
serverInfo gitea-mcp 0.1.0 and cad aed2aaf. Nothing about the services or the
proxying is blocked.

What is actually blocked is delivery into the session environment. By design no
single identity on koala reads both vaults, and the session env comes from one
`op run --env-file ~/.op-env` under the HomeLab-only token. A mixed-vault file
does not degrade gracefully: tested on a two-line copy, `op run` aborts on the
unresolvable reference and BRAIN_MCP_TOKEN goes unresolved with it — so
appending to ~/.op-env would take out the MCP servers that currently work.

Refs #32, #33
Bump-Type: patch

.mcp.json

@@ -14,7 +14,7 @@
     }
   },
   "_parked": {
-    "_reason": "cad and gitea-mcp are proxied and reachable (tailscale serve 8445 -> 127.0.0.1:31877, 8446 -> 127.0.0.1:30340; both answer 401 unauthenticated, so auth is enforced and the path is right). They stay parked because their static tokens live in the 1Password AgentSecrets vault, and this host's op identity sees only HomeLab -- 'op vault list' returns HomeLab alone, and resolving op://HomeLab/gitea-mcp-shared-token/password or op://HomeLab/CAD_STATIC_TOKEN/password fails with 'could not find item'. That is infra#224 (AgentSecrets not visible to koala's service account), NOT the OAuth-discovery bug both issues warned about. Enabling is: make the vault visible, add the two op:// references to ~/.op-env, move these entries into mcpServers. See mathias/skills#32 and #33.",
+    "_reason": "cad and gitea-mcp are proxied, reachable and AUTHENTICATING: tailscale serve 8445 -> 127.0.0.1:31877 and 8446 -> 127.0.0.1:30340; an MCP initialize with the correct bearer returns 200 from both (serverInfo gitea-mcp 0.1.0, cad aed2aaf). They stay parked only because nothing puts those two tokens into the session environment. Both live in the 1Password AgentSecrets vault, and by deliberate design (infra#224, closed) no single identity on koala reads both vaults: koala-homelab is HomeLab-only and resolves ~/.op-env, koala-agentsecrets-write is AgentSecrets-only and lives in ~/.op-agent-write.env. Adding an AgentSecrets reference to ~/.op-env does NOT degrade gracefully -- `op run` fails wholesale and every other token, BRAIN_MCP_TOKEN included, goes unresolved with it. Enabling needs a read-scoped AgentSecrets identity in the session-env path; see mathias/skills#32, #33.",
     "cad": {
       "type": "http",
       "url": "https://koala.tail30472e.ts.net:8445/mcp",