fix: --yolo and other flags silently dropped when placed before 'chat' subcommand (#5145)

When --yolo, -w, -s, -r, -c, and --pass-session-id exist on both the parent
parser and the 'chat' subparser with explicit defaults (default=False or
default=None), argparse's subparser initialization overwrites the parent's
parsed value. So 'hermes --yolo chat' silently drops --yolo, making it appear
broken.

Fix: use default=argparse.SUPPRESS on all duplicated arguments in the chat
subparser. SUPPRESS means 'don't set this attribute if the user didn't
explicitly provide it', so the parent parser's value survives through.

Affected flags: --yolo, --worktree/-w, --skills/-s, --pass-session-id,
--resume/-r, --continue/-c.

Adds 15 regression tests covering flag-before-subcommand, flag-after-subcommand,
no-subcommand, and env var propagation scenarios.

hermes_cli/main.py

@@ -4033,7 +4033,7 @@ For more help on a command:
     chat_parser.add_argument(
         "-s", "--skills",
         action="append",
-        default=None,
+        default=argparse.SUPPRESS,
         help="Preload one or more skills for the session (repeat flag or comma-separate)"
     )
     chat_parser.add_argument(
@@ -4055,6 +4055,7 @@ For more help on a command:
     chat_parser.add_argument(
         "--resume", "-r",
         metavar="SESSION_ID",
+        default=argparse.SUPPRESS,
         help="Resume a previous session by ID (shown on exit)"
     )
     chat_parser.add_argument(
@@ -4062,14 +4063,14 @@ For more help on a command:
         dest="continue_last",
         nargs="?",
         const=True,
-        default=None,
+        default=argparse.SUPPRESS,
         metavar="SESSION_NAME",
         help="Resume a session by name, or the most recent if no name given"
     )
     chat_parser.add_argument(
         "--worktree", "-w",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Run in an isolated git worktree (for parallel agents on the same repo)"
     )
     chat_parser.add_argument(
@@ -4088,13 +4089,13 @@ For more help on a command:
     chat_parser.add_argument(
         "--yolo",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Bypass all dangerous command approval prompts (use at your own risk)"
     )
     chat_parser.add_argument(
         "--pass-session-id",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Include the session ID in the agent's system prompt"
     )
     chat_parser.add_argument(