chore: bump to 0.5.3 for the asset-admission work (#179)

Patch: no schema change, no rail change, nothing that alters what the agent
trades or when. Ships #176, #177 and #178.

The reason to cut this rather than wait is #176's fix to `DATA_DERIVED_FAILURES`,
which is a reporting bug live on the deployment right now: `history` was missing
from the tag set that marks a failure as downstream of an empty cache, so
`keel assets propose` and `keel assets holdings --screen` printed
`x history: 0 daily bars < 1460 required` directly beneath their own note saying
the verdict was about missing data rather than about the asset. An asset nobody
had ever fetched was reported as too young to trade.

Also in: the TUI can now reach the admission gate (`screen`/`propose`/`discover`,
read-only, `discover` network-gated behind an explicit keypress like `f`); the
non-UTF-8 shortlist hole that broke `build_propose_view`'s documented never-raises
contract; and the header now shows the patch segment, so 0.5.1 and 0.5.3 no longer
render identically as `v0.5`.

uv.lock relocked in the SAME commit, per 0.5.0-0.5.2. Verified with
`uv sync --frozen`, which accepted the lock and rewrote nothing.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: eaitbrahim

packages/keel-broker-api/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-api"
-version = "0.5.2"
+version = "0.5.3"
 description = "Broker port, domain types, capability model, and conformance suite for keel"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core"]

packages/keel-broker-coinbase/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-coinbase"
-version = "0.5.2"
+version = "0.5.3"
 description = "Coinbase Advanced Trade adapter for keel"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core", "keel-broker-api", "coinbase-advanced-py>=1.8.4"]

packages/keel-broker-fake/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "keel-broker-fake"
-version = "0.5.2"
+version = "0.5.3"
 description = "A deliberately divergent second broker adapter, to keep the port honest"
 requires-python = ">=3.14.4"
 dependencies = ["keel-core", "keel-broker-api"]

packages/keel-core/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "keel-core"
-version = "0.5.2"
+version = "0.5.3"
 description = "Shared domain types, configuration, and logging for keel"
 requires-python = ">=3.14.4"
 dependencies = ["pyyaml>=6.0.3", "python-dotenv>=1.2.2"]

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "keel-trader"
-version = "0.5.2"
+version = "0.5.3"
 description = "Offline-first, broker-agnostic, rule-based spot-trading agent (halal policy by default)"
 readme = "README.md"
 authors = [