add a native startup banner to the empty Claude pane (T-149)

Replaces the bare "Waiting for Claude…" empty state with ClaudeBanner:
clide's own logo, a "Claude" label, the session role (primary /
secondary N), the workspace (home-collapsed), the tmux status line, and
a warming-up hint. ConversationView gains an optional emptyState widget;
the pane supplies the banner from data it already has.

Fully owned — no tmux capture-pane, no Anthropic artwork. The "Claude"
label uses Anthropic's published accent #d97757 nominatively; recorded
under a new trademark_notices section in assets/licenses.yaml (clide is
unaffiliated, bundles no Anthropic logo/artwork). Also fixes a stale
forkpty->pty reference in that file.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

assets/licenses.yaml

@@ -226,4 +226,20 @@ dev_dependencies:
     license: BSD-3-Clause
     purpose: >-
       Dart test runner for the Flutter-free PTY tests under
-      `dart test --tags forkpty` (flutter_test is used elsewhere).
+      `dart test --tags pty` (flutter_test is used elsewhere).
+
+# Trademark / brand notices — third-party marks clide references but does
+# NOT bundle. No artefact ships for these; tracked here for audit
+# completeness and to record the nominative-use basis.
+trademark_notices:
+  - mark: Claude name + accent colour (#d97757)
+    owner: Anthropic, PBC
+    reference: https://github.com/anthropics/skills/tree/main/skills/brand-guidelines
+    usage: >-
+      Nominative use only. "Claude" identifies the CLI that clide
+      integrates with; #d97757 is Anthropic's published Claude accent
+      colour, used solely to mark Claude's own messages/labels in the
+      conversation UI (not as clide's brand colour). clide is not
+      affiliated with, endorsed by, or partnered with Anthropic, bundles
+      no Anthropic logo or brand artwork, and ships its own logo. CLAUDE
+      is a registered trademark of Anthropic, PBC.