refactor: split cli.go into focused files by responsibility

Extract cli.go into four dedicated files to improve separation of concerns
and readability: cli_flags.go (flag parsing), cli_backend.go (backend init),
cli_commands.go (command handlers), cli_dispatch.go (command routing).
Fix inaccurate comments on logMsg/warn that claimed declaration order matters
in Go; package-level functions are resolved across the whole file.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/internal/cli/cli_flags.go b/internal/cli/cli_flags.go
new file mode 100644
index 0000000..a3673ad
--- /dev/null
+++ b/internal/cli/cli_flags.go
@@ -0,0 +1,43 @@
+// Package cli — flag parsing helpers.
+//
+// This file contains the low-level argv scanning functions that extract
+// global flags (--backend, --kdbx-path) before the command is dispatched.
+// They are intentionally separate from the backend factory and the CLI struct
+// so that flag parsing can be tested and reasoned about in isolation.
+package cli
+
+// parseBackendFlag scans argv for a "--backend VALUE" pair and returns the
+// backend name and the remaining argv with that pair removed.  Returns ("", argv)
+// when no --backend flag is present.  The flag may appear anywhere in argv.
+//
+// Note: only the space-separated form "--backend VALUE" is supported.
+// The equals form "--backend=VALUE" is NOT parsed and will be silently ignored
+// (treated as an unknown argument that propagates to the command dispatcher).
+func parseBackendFlag(argv []string) (string, []string) {
+	return parseFlagValue("--backend", argv)
+}
+
+// parseKDBXPathFlag scans argv for a "--kdbx-path VALUE" pair and returns the
+// path and the remaining argv with that pair removed.  Returns ("", argv) when
+// no --kdbx-path flag is present.  Overrides cfg.KDBXPath for the process
+// lifetime without modifying the config file.
+//
+// Note: only the space-separated form "--kdbx-path VALUE" is supported.
+func parseKDBXPathFlag(argv []string) (string, []string) {
+	return parseFlagValue("--kdbx-path", argv)
+}
+
+// parseFlagValue is the shared implementation for single-value flag extraction.
+// It scans argv for a "FLAG VALUE" pair, removes it, and returns the value and
+// the remaining argv.  Returns ("", argv) when the flag is absent.
+func parseFlagValue(flag string, argv []string) (string, []string) {
+	for i, arg := range argv {
+		if arg == flag && i+1 < len(argv) {
+			remaining := make([]string, 0, len(argv)-2)
+			remaining = append(remaining, argv[:i]...)
+			remaining = append(remaining, argv[i+2:]...)
+			return argv[i+1], remaining
+		}
+	}
+	return "", argv
+}