test sweep: cover TerminalView widget (T-91)

Adds test/terminal/terminal_view_test.dart — 14 widget tests
covering the StatefulWidget that wires gesture / keyboard / scroll
plumbing around a `Terminal`:

- Construction smoke tests (default, externally-supplied
  controller / focusNode / scrollController, hardwareKeyboardOnly,
  readOnly + hardwareKeyboardOnly).
- Pointer-signal handling: PointerScrollEvent → PgUp/PgDown
  keyInput; non-scroll PointerSignalEvent ignored.
- didUpdateWidget swap of focusNode / controller / scrollController
  (auto-created previous instance gets disposed cleanly).
- Hardware key event flowing through to Terminal.keyInput.
- cursorRect / globalCursorRect after layout.
- requestKeyboard / closeKeyboard as no-ops when no edit state is
  mounted; hasInputConnection false when no input connection is
  open.
- Selection survival when the widget unmounts but an
  externally-owned controller stays alive.

Coverage delta:
- terminal_view.dart: 0/188 → 151/188 (80.3%).
- Total project: 59.82% → 65.76%; coverage_floor bumped 59 → 65.

The remaining ~20% in terminal_view.dart sits in
gesture / IME / keyboard-event plumbing (`_onTapUp`, `_onTapDown`,
secondary-tap callbacks, `_onInsert`, `_onComposing`,
`_handleKeyEvent` shortcut path, `_onKeyboardShow`,
`_onEditableRect`, `_scrollToBottom`). These are reachable only
through full pointer / IME simulation that's better suited to
`integration_test/` than widget tests — leaving them for a
later integration-test pass rather than papering over with
brittle gesture mocking.

Co-Authored-By: Claude <noreply@anthropic.com>

pubspec.yaml

@@ -18,7 +18,7 @@ repository: https://github.com/postmeridiem/clide
 
 # Pre-push line-coverage floor. Ratchets up only — see D-66.
 # Reading: `awk -F: '/^coverage_floor:/ {gsub(/ /,"",$2); print $2}' pubspec.yaml`.
-coverage_floor: 59
+coverage_floor: 65
 
 # Project metadata (was project.yaml, folded in per D-056).
 # version: above is the single source of truth. The Makefile reads