Install fpcalc in the image; release 0.21.0

The image installed ffmpeg but not libchromaprint-tools, so hark fingerprint
and discover-ads would have been inert in the deploy rather than broken:
fpcalc_available() returns False, the command exits tidily, and a
healthy-looking container silently never matches an ad. Same defect adscrub
0.8.0 fixed in its own image.

Bumps __version__ alongside pyproject, which has drifted in sibling repos.

CHANGELOG.md

@@ -7,6 +7,36 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.21.0] - 2026-07-23
+
+### Added
+
+- **`hark fingerprint`** — matches episode AUDIO against ad recordings already confirmed in
+  this corpus (adscrub 0.8.0's fingerprint tier). It costs no tokens and needs no transcript,
+  so it runs while the Claude-driven pipeline stays disabled. Verified against a read-only
+  snapshot of the live database: **337 ad spans across 82 of 82 episodes, 0 failures, no model
+  called.**
+- **`hark discover-ads --show <id>`** — cold start for one show, finding ads by matching that
+  show's episodes against each other, with no confirmed ads to seed from. Scoped to a single
+  show deliberately: recurrence is measured against whatever set it is given, and this database
+  holds ~70 unrelated feeds that share no ad pool. Its `recur` spans are inference and are not
+  cut by default.
+- Both commands go per-episode rather than through adscrub's bulk helpers, so the per-show
+  `ad_stripping_enabled` toggle actually applies — the same reason `repeats` does.
+
+### Fixed
+
+- **`libchromaprint-tools` (fpcalc) added to the image.** Without it the two commands above are
+  not broken but inert: they exit tidily and silently match nothing, behind a container that
+  looks healthy.
+- **`_PrecomputedDetector` accepts the `skip` argument** that `AdSpanDetector.detect` grew in
+  adscrub 0.8.0. `LayeredDetector` passes it positionally, so without this every
+  `load-ad-detections` record failed with a `TypeError`.
+
+### Changed
+
+- adscrub pinned 0.7.2 -> 0.8.0.
+
 ## [0.20.0] - 2026-07-15
 
 ### Added

Dockerfile

@@ -99,7 +99,11 @@ RUN if [ "$GPU" = "1" ]; then \
 # matches TrueNAS SCALE's standard "apps" account, so files land owned by
 # the same user/group as every other app on that host; harmless elsewhere.
 # ffmpeg is for adscrub's cut.py, called as a library (see cli.py).
-RUN apt-get update && apt-get install -y --no-install-recommends gosu ffmpeg \
+# libchromaprint-tools provides fpcalc, which adscrub's fingerprint tier shells out to for
+# `hark fingerprint`/`discover-ads`. Without it those commands are not broken but INERT:
+# fpcalc_available() returns False, the command exits with a tidy message, and a
+# healthy-looking container silently never matches an ad.
+RUN apt-get update && apt-get install -y --no-install-recommends gosu ffmpeg libchromaprint-tools \
     && rm -rf /var/lib/apt/lists/* \
     && groupadd --gid 568 hark \
     && useradd --system --uid 568 --gid 568 --no-create-home hark

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "hark"
-version = "0.20.0"
+version = "0.21.0"
 description = "Cross-podcast topic index and discovery service"
 readme = "README.md"
 requires-python = ">=3.12"

src/hark/__init__.py

@@ -1,3 +1,3 @@
 """hark — cross-podcast topic index and discovery service."""
 
-__version__ = "0.20.0"
+__version__ = "0.21.0"

uv.lock

@@ -242,7 +242,7 @@ wheels = [
 
 [[package]]
 name = "hark"
-version = "0.20.0"
+version = "0.21.0"
 source = { editable = "." }
 dependencies = [
     { name = "adscrub" },