fix(deps): resolve all RUSTSEC security advisories (#561)

Update dependencies to fix security vulnerabilities:

- wasmtime v29 → v41: Fixes RUSTSEC-2025-0118 (shared memory API),
  RUSTSEC-2025-0046 (fd_renumber panic), RUSTSEC-2026-0006 (f64.copysign
  segfault), RUSTSEC-2025-0057 (fxhash unmaintained), RUSTSEC-2024-0436
  (paste unmaintained)
- scraper v0.22 → v0.25: Removes fxhash transitive dependency
- ratatui v0.29 → v0.30: Fixes RUSTSEC-2026-0002 (lru unsound iteration)
- crossterm v0.28 → v0.29: Required for ratatui v0.30 compatibility
- tui-textarea: Updated to git version for ratatui v0.30 support

All RUSTSEC ignore entries removed from .cargo/audit.toml.
Code changes: Updated MockBackend trait impl and lifetime annotations
for ratatui v0.30 API changes.

Author: echobt

.cargo/audit.toml

@@ -6,42 +6,8 @@
 # easily upgraded, typically due to deep dependency chains (e.g., wasmtime).
 
 [advisories]
-# These advisories are either:
-# 1. False positives for our use case
-# 2. In transitive dependencies we cannot easily update
-# 3. Low severity issues being tracked for future resolution
-#
-# All wasmtime issues are due to using v29.0.1 via cortex-plugins.
-# Upgrading wasmtime is a significant effort tracked separately.
-ignore = [
-    # wasmtime v29.0.1 - Unsound API access to WebAssembly shared linear memory
-    # Severity: low (1.8)
-    # We don't expose raw WebAssembly memory APIs to untrusted code
-    "RUSTSEC-2025-0118",
-
-    # wasmtime v29.0.1 - Host panic with fd_renumber WASIp1 function
-    # Severity: low (3.3)
-    # Limited exposure - panic doesn't compromise security
-    "RUSTSEC-2025-0046",
-
-    # wasmtime v29.0.1 - Segfault with f64.copysign operator on x86-64
-    # Severity: medium (4.1)
-    # Tracked for wasmtime upgrade
-    "RUSTSEC-2026-0006",
-
-    # fxhash v0.2.1 - unmaintained
-    # Transitive dependency via selectors/scraper and wasmtime
-    "RUSTSEC-2025-0057",
-
-    # paste v1.0.15 - unmaintained
-    # Transitive dependency via wasmtime and ratatui
-    "RUSTSEC-2024-0436",
-
-    # lru v0.12.5 - unsound IterMut implementation
-    # Transitive dependency via ratatui
-    # We don't use LRU cache iteration mutably
-    "RUSTSEC-2026-0002",
-]
+# No longer needed - wasmtime updated to v41, ratatui to v0.30
+ignore = []
 
 # Warn on informational advisories (unmaintained, unsound, etc.)
 informational_warnings = ["unmaintained", "unsound", "notice"]