stratify 1.0.0

The stability release. From here, a breaking change to anything public is a
major version, so the 0.4-era caveat about minor bumps is retired along with
the number.

stratify absorbs the unpublished loggingkit crate. One crate, two namespaces:
stratify::config is the configuration half, stratify::logging is a
non-blocking tracing facade, and stratify::init stands both up in one call.
The logging half is behind the logging feature and a config-only build
compiles none of it — CI proves that on every push by failing if the default
dependency tree contains tracing-subscriber, tracing-appender or any
opentelemetry crate.

Changed

• Breaking: the config API moved from the crate root into
  stratify::config, and the types shed their prefixes now that the module
  carries the name: ConfigBuilder → config::Builder, ConfigError →
  config::Error, ConfigStore → config::Store. Source and the source
  types live under config::source.
• The minimum supported Rust version is now declared: 1.88.0.

Added

• stratify::logging (feature logging): console, JSON, file and syslog
  sinks, all non-blocking; per-sink filters; runtime filter reload; sampling
  and rate-limit gates; size- and time-based file rotation with retention;
  custom line formatters; redaction; panic capture; queue-depth and
  dropped-line accounting. Formerly the loggingkit facade, imported here
  without its history and with its legacy pre-facade API (LogBuilder,
  LogStore, the sink module) left behind.
• logging::settings::Settings (and per-sink *Settings blocks), a serde
  schema read from a config [Store] with Settings::from_store. The logging
  half does no parsing of its own — TOML, YAML, JSON and environment layering
  are the config half's job, in one place. The old from_file, and the toml
  dependency it carried, are gone.
• stratify::init and init_with (feature logging): read configuration
  (file < environment < .env), build logging from its [logging] block,
  install the subscriber, and return the Bootstrap pair. The first record
  the subscriber carries names the sources that resolved, so a wrong
  precedence stack is visible instead of silent.
• Features appinsights (Azure Application Insights export with trace
  correlation) and compression (gzip retired log files), both implying
  logging.
• Full settings parity: [logging.filters] (per-sink directives), redact,
  capture_panics, [logging.global_fields], [logging.syslog] and
  [logging.app_insights] are all expressible in configuration, so "described
  rather than coded" covers the whole builder surface. The app_insights
  block names the key the connection string is found under rather than
  holding the value, so the file stays safe to commit; an explicit block whose
  secret is missing is a startup error, not a silently absent exporter. A bad
  level, an unknown syslog facility, or a block needing a feature that is
  not compiled in all fail loudly at startup naming the offending key —
  Settings::to_builder is fallible now for exactly that reason.
• AppInsightsConfig::with_sample_rate, bounding the fraction of traces
  exported (0.0..=1.0, parent-based so a trace is kept or dropped whole).
  Exporting every span is an Application Insights bill that grows linearly
  with traffic; this is the knob. Log records are not sampled — per-sink
  filters are the tool for those. Also settable as sample_rate in the
  [logging.app_insights] block.
• init reads rust_log from the store when no explicit level is set, so a
  RUST_LOG written in .env obeys the store's precedence instead of
  silently losing to a shell export — the builder's own fallback reads the
  process environment, which a .env loaded as a source never touches.
  Sourced from configuration it is validated strictly: a typo is a startup
  error naming the key.
• AzureAppConfigSource::with_key_vault_resolution, resolving Key Vault
  references into the secrets they point at, reusing the source's credential
  against the vault data plane. Off by default because resolution widens the
  source's reach from one store to every vault the references name; with it
  off, encountering a reference is an error naming the key — loud, rather
  than a JSON envelope masquerading as a configuration value.
• stratify::logging::EnvFilter, re-exported so with_filter and
  reload_filter can be called without taking tracing-subscriber as a
  direct dependency.