fix: improve issue ID prefix extraction for word-like suffixes

Refine ExtractIssuePrefix to better distinguish hash IDs from English
words in multi-part issue IDs. Hash suffixes now require digits or be
exactly 3 chars, preventing "test", "gate", "part" from being treated
as hashes. This fixes prefix extraction for IDs like "vc-baseline-test".

Also updates git hooks to use -q flag and adds AGENTS.md documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/utils/id_parser_test.go

@@ -358,9 +358,9 @@ func TestExtractIssuePrefix(t *testing.T) {
 			expected: "alpha-beta", // Last hyphen before numeric suffix
 		},
 		{
-			name:     "multi-part non-numeric suffix",
+			name:     "multi-part non-numeric suffix (word-like)",
 			issueID:  "vc-baseline-test",
-			expected: "vc-baseline", // Alphanumeric suffix uses last hyphen (GH#405 fix)
+			expected: "vc", // Word-like suffix (4+ chars, no digit) uses first hyphen (bd-fasa fix)
 		},
 		{
 			name:     "beads-vscode style prefix",