security: add the capability and policy layer as the only path to action

Phase 12 (ADR-0005). Capabilities are registered in code with parameter
schemas, risk classes and default effects; sudo_shell and delete_database
are locked to DENY and cannot be relaxed. Policies are scoped globally or
per mind with capability, target glob, action kind and optional hour
window; evaluation is deterministic, most specific wins, and ties go to
the stricter effect. Invoke is the single entry point: it refuses
dreaming and replay contexts, validates parameters (unknown keys, non
http URLs and path traversal rejected), evaluates policy and session
grants, hashes the exact request and records a policy_decision event.
ALLOW executes with timeout and panic isolation and turns textual output
into a tool-trust observation; ASK creates an approval request bound to
the hash with an alert notification; DENY is counted and recorded.

Operators approve once, approve for a time-boxed session grant, deny
with a note, or modify parameters (re-validated, re-hashed, original
kept in the append-only decision log). The self-model's capability list
is recomputed from effective policy on start and on every policy change.
The act process maps fetch requests to http.fetch and the action handler
invokes through the layer; replies report capabilities and outcomes.

Policy matrix and approval centre pages, dashboard count, API, CLI
(approvals, policy, invoke) and docs/capabilities.md.

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes to Noema are recorded here. Format follows Keep a Changelog;
 ## [Unreleased]
 
 ### Added
+- Phase 12 capabilities: single policy-governed action path with ALLOW/ASK/DENY rules, locked capabilities, request-bound approvals (once, session, modified), tool output as tool-trust observations, self-model synchronisation, approval centre and policy matrix.
 - Phase 11 relationship graph: mind-scoped entities with aliases, evidenced typed edges, links to memories/beliefs/events, deterministic extraction from conversation and observations, merge/distinct corrections, bounded canvas explorer, API and CLI.
 - Phase 10 background cognition: metacognitive self-checks, scheduled reflection with lessons, episode consolidation into evidenced generalisations with operator review, internal narrative, thresholded notifications with aggregation.
 - Phase 9 motivation: goal tree with attention relevance, closed drive set and rule-driven affect state with decay and weight modulation, explicit predictions with deterministic resolution, prediction errors feeding beliefs, calibration dashboard, curiosity questions becoming investigation goals.