feat(worker)!: promote to v1.0.0 — add Len() to Provider, bump deps to v1

Add Len() int to Provider interface; returns current queue depth for
observability and test assertions. Bump launcher and logz to v1.0.1.
Go directive bumped to 1.26. API committed as stable.

CHANGELOG.md

@@ -5,6 +5,25 @@ All notable changes to this module will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this module adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.0.0] - 2026-05-12
+
+### Added
+
+- `Len() int` on `Provider` — returns the current number of tasks waiting in the queue.
+  Useful for observability, logging backpressure state, and tests.
+
+### Changed
+
+- Go directive bumped from 1.25 to 1.26
+- `launcher` and `logz` dependencies bumped to v1.0.1
+
+### Stabilization
+
+- API committed as stable. `Task`, `Provider`, `Component`, `Config`, and `New` are
+  unchanged from v0.9.0 except for the addition of `Len`.
+
+[1.0.0]: https://code.nochebuena.dev/go/worker/compare/v0.9.0...v1.0.0
+
 ## [0.9.0] - 2026-03-18
 
 ### Added