0.11 A3: network approvals keyed on host + protocol + port, with "Don't allow this host"

[Hmbown]

Today: network grants are keyed as net:{host} only (approval_cache.rs:~81-125, parse_host :~390). Scheme and port are dropped, so an approval for one port or protocol covers every other one on that host. NetworkSessionCache is a third, separate store, and its approve and deny methods have no production callers.

Change

1. Parse the full target. parse_net_target returns a NetKey:

   • host: lowercase, normalized to IDNA
   • protocol: http, https, ws or wss
   • port: the explicit port, or the scheme default

   The grouping key becomes net:{proto}://{host}:{port}. An unparseable URL gets its own digest.

2. One store. Conversation-scope grants and denies go into A1's GrantStore. Delete NetworkSessionCache and its unused methods. NetworkPolicyDecider::evaluate checks GrantStore first; a deny still wins.

3. Repo scope and "Don't allow this host". Persist these as existing-schema rules: ToolAskRule{tool:"network", command:"https://host:443", workspace, action}. Older binaries parse them and treat them as inert. Relax the Deny bail in persist_rules_from_approval for tool=="network" only.

4. Card choices. Use the four §19 choices. "Don't allow" offers two versions: this time, or always for this host in this repo.

Tests

• net_grant_keyed_by_protocol_and_port
• network_repo_deny_beats_conversation_allow
• network_rule_toml_parses_with_old_schema
• a compile-time guard that NetworkSessionCache is removed
• oauth tests moved onto GrantStore

Size: M. Blocked by: A1. Spec: codewhale-ops approvals/specs/A-grants-authority-0.11.md (A3).