fix(config): trust APPS_SCHEMA float type over an int default in get_arg() (#4925)

[chalfontchubby]

Fixes #4925.

Problem

get_arg() coerces its return value on the type of the default it was handed, not on the key's declared APPS_SCHEMA type, and applies that coercion to whatever value was resolved — real configured value or not. So get_arg("solcast_poll_hours", 8) ran a genuinely configured 4.8 through int(float(value)) and returned 4, shortening the Solcast poll TTL from 4.8h to 4h and pushing a two-site hobbyist account past its 10 poll/day quota into nightly HTTP 429s. Nothing warned: validate_config() checks the raw apps.yaml value against the float schema and passes it, so apps.yaml still reads 4.8 while the runtime behaves as 4.

Why not the issue's suggested fix

The issue proposes normalising int defaults inside Components.initialize(). That only covers the component-framework path. Auditing every float-declared APPS_SCHEMA key against its get_arg call sites found three more truncating reads that fix would miss — octopus_saving_session_rate and octopus_saving_session_min_octopoints_per_kwh are read directly from octopus.py, not through a component arg spec — plus a fifth affected component arg (alphaess_api_delay) the issue's table didn't list.

Fix

Fixed at the source in get_arg() (userinterface.py): promote an int default to float whenever APPS_SCHEMA declares the key float, before the coercion at the end of the function ever sees it. One normalisation point, mirroring where #4441 fixed the equivalent CONFIG_ITEMS-route bug in get_ha_config(), so no call site — present or future — can change a float-declared key's runtime type by writing 8 instead of 8.0.

Not included: the issue's second ask (a warning on lossy coercion). With the root cause fixed at the source, a remaining truncation means the schema genuinely declares the key an integer, so the warning would fire on intended behaviour every ~5 minutes on a routine sensor read.

Testing

• test_get_arg_float_schema_int_default_not_truncated — the reported 4.8 → 288min case, an axle_pence_per_kwh money case, a direct (non-component) call site, unset-fallback typing, and negative controls for integer-declared and boolean keys.
• test_component_arg_specs_resolve_float_declared_keys_as_float — sweeps every COMPONENT_LIST arg spec whose APPS_SCHEMA type is float, resolving each the way Components.initialize() does (currently 9 keys), so it stays correct for specs added later rather than asserting on today's literals.
• Both verified to fail against unpatched userinterface.py and pass with the fix.
• ./run_all --quick green, ./run_pre_commit green.

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Written by Claude on behalf of @chalfontchubby.

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