Keep the sub-app's deprecated flag in add_typer()

[VenishPaneliya]

Typer.add_typer() declares its deprecated parameter as a plain False, while every other setting in the same signature uses the Default() sentinel — including hidden, which sits directly above it:

        hidden: Annotated[...] = Default(False),
        deprecated: Annotated[...] = False,          # <- the odd one out

solve_typer_info_defaults() uses that sentinel to tell "the caller passed this to add_typer()" apart from "the caller said nothing":

        # Priority 1: Value was set in app.add_typer()
        if not isinstance(value, DefaultPlaceholder):
            values[name] = value
            continue
        # Priority 2: Value was set in @subapp.callback()
        ...
        # Priority 3: Value set in subapp = typer.Typer()

A bare False is not a DefaultPlaceholder, so Priority 1 always fires and Priorities 2 and 3 are never reached. A sub-app that marked itself deprecated silently loses that flag the moment it is added to a parent.

Reproduction

import typer

app = typer.Typer()
sub_app = typer.Typer(deprecated=True)

@sub_app.command()
def sub_command():
    """Sub command."""

app.add_typer(sub_app, name="sub")

--help on the parent:

│ sub                                                                          │

expected:

│ sub                                                            (deprecated)  │

Why this is the default and not a judgement call

Two controls, same shape, both behave correctly:

Case	Result
sub_app = typer.Typer(hidden=True) — sibling, Default()-wrapped	✅ propagates
app.add_typer(sub_app, deprecated=True) — passed at the call site	✅ shows (deprecated)
sub_app = typer.Typer(deprecated=True) — this bug	❌ silently dropped

So the plumbing is fine end to end; only the default is wrong.

TyperInfo is constructed in exactly three places, and all three flow through solve_typer_info_defaults():

	deprecated default
Typer.__init__	Default(False)
Typer.callback()	Default(False)
Typer.add_typer()	False ←

Typer.command() also uses a bare False, but that one builds a CommandInfo, which never goes through the solver — so it is correctly different and is left alone here.

Change

One token: ] = False, → ] = Default(False),. Default is already imported in the module.

Tests

Added test_add_typer_keeps_sub_app_deprecated to tests/test_deprecation.py, parametrised over rich / non-rich the same way tests/test_hidden.py does, since the marker renders as (deprecated) under Rich and (DEPRECATED) without it.

• Against master: both parametrisations fail
• With the change: pass
• Full suite before: 1379 passed, 18 skipped, 2 xfailed
• Full suite after: 1381 passed, 18 skipped, 2 xfailed — no other test changes behaviour
• ruff check and ruff format --check clean on both changed files
• mypy typer reports the same 6 pre-existing errors before and after (identical set); none in main.py