homelab v0.8.2: fix memory recall truncating multibyte UTF-8 mid-character

emo's Claude Code sessions hit "UserPromptSubmit hook error" on almost every
prompt. Root cause: the homelab-memory-recall.py UserPromptSubmit hook runs
`homelab memory recall <prompt>` and strict-decodes its stdout. printMemories
truncated each memory's preview with a BYTE slice (c[:240]), which cuts through
the middle of a 2-byte Cyrillic character and emits invalid UTF-8 (a dangling
0xd0 lead byte). The hook's subprocess.run(text=True) then raised
UnicodeDecodeError — not caught by its `except (TimeoutExpired, OSError)` — so
the hook exited non-zero and Claude surfaced the error. It is Cyrillic-specific
(ASCII has no multibyte chars to split), so it bit emo (Bulgarian prompts) every
turn while English users almost never saw it.

Two-layer fix:
- cli: truncatePreview() now counts RUNES, not bytes, so the preview never
  splits a character. Regression test asserts valid UTF-8 on a long Cyrillic
  string. Fixes the root for every consumer of `memory recall` / `memory list`.
- hook: subprocess.run gains errors="replace" and the except is broadened to
  honor the script's own "best-effort, exit 0" contract — so a truncated or
  otherwise odd payload can never again surface as a hook error.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cli/memory_test.go

@@ -5,8 +5,31 @@ import (
 	"os"
 	"strings"
 	"testing"
+	"unicode/utf8"
 )
 
+func TestTruncatePreviewKeepsValidUTF8(t *testing.T) {
+	// Byte-slicing a long Cyrillic string at 240 splits a 2-byte rune and emits
+	// invalid UTF-8 — the bug that crashed the recall hook. truncatePreview must
+	// cut on a rune boundary and always stay valid UTF-8.
+	long := strings.Repeat("я", 300) // 300 runes / 600 bytes
+	got := truncatePreview(long, 240)
+	if !utf8.ValidString(got) {
+		t.Fatalf("truncatePreview produced invalid UTF-8: %q", got)
+	}
+	if r := []rune(got); len(r) != 241 || string(r[:240]) != strings.Repeat("я", 240) || r[240] != '…' {
+		t.Fatalf("truncatePreview = %d runes, want 240 Cyrillic + ellipsis", len(r))
+	}
+	// Short multibyte strings pass through untouched (no ellipsis).
+	if got := truncatePreview("кратко", 240); got != "кратко" {
+		t.Fatalf("short string altered: %q", got)
+	}
+	// ASCII boundary still works.
+	if got := truncatePreview(strings.Repeat("a", 500), 240); got != strings.Repeat("a", 240)+"…" {
+		t.Fatalf("ascii truncation wrong: %q", got)
+	}
+}
+
 func TestResolveMemoryBase(t *testing.T) {
 	old1, old2 := os.Getenv("CLAUDE_MEMORY_API_URL"), os.Getenv("MEMORY_API_URL")
 	defer func() { os.Setenv("CLAUDE_MEMORY_API_URL", old1); os.Setenv("MEMORY_API_URL", old2) }()