MCP v2 PR-1: policy engine + audit log + Config/Audit/Policy panel tabs

Foundation for Claude-drives-the-workspace writes. Nothing wired
end-to-end yet (App.tsx dispatcher comes next); this lands the
machinery + UI.

mcp_policy.rs (new) — three-tier allow/ask/deny policy with
deny-first precedence and a compiled-in non-overridable hard-deny
list (10 patterns covering rm -rf /, fork bombs, mkfs on device, dd
to raw disk, /etc/passwd overwrite, curl|sh, chmod -R 777 /, etc.).
Shell-operator-aware glob matcher mirroring Claude Code's Bash(*)
syntax. Restrictive default — empty policy means every non-hard-
denied call falls to Ask. Persisted to mcp-policy.json in
app_config_dir. Includes a PolicyClassifier scaffold (no-op) for a
future v2.1 LLM-classifier hook. 1152 lines incl. ~100 unit + fuzz
tests covering the matchers and lookalike negatives.

mcp.rs — TileService now holds AppHandle + Arc<PendingActions>
(oneshot registry keyed by uuid). New async dispatch_action helper
runs the policy check, emits "mcp://request" for the frontend to
handle, awaits a oneshot reply (30s timeout), then emits "mcp://
audit" with the outcome regardless. set_label tool wired through
this path as the demo for PR-1b's dispatcher.

commands.rs / lib.rs — new Tauri commands mcp_action_reply,
mcp_policy_load, mcp_policy_save; PendingActions registered as
managed state.

McpPanel.tsx — refactored into Config / Audit / Policy tabs.
AuditTab listens on mcp://audit, keeps a 200-entry ring with
ok/denied/failed chips. PolicyTab edits the allow/ask/deny buckets
(stacked vertically — three columns overflowed the panel) and shows
the hard-deny rules read-only at the bottom with "Cannot be
disabled" badges. Themed scrollbar on mcp-body to match xterm panes.

Caveat: set_label calls from Claude will currently time out — the
App.tsx side that listens on mcp://request and replies via
mcp_action_reply lands in PR-1b.

Co-authored by Sonnet (policy engine, backend plumbing, panel UI)
and Haiku (hard-deny fuzz test suite); integration + bug fixes here.

src-tauri/Cargo.toml

@@ -37,6 +37,7 @@ tower = "0.5"
 tokio-util = { version = "0.7", features = ["rt"] }
 rand = "0.9"
 hex = "0.4"
+regex = "1"
 
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"