feat(examples): price-alert Chainlink oracle reader (BLEU-846)

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "crates/shepherd-sdk-test",
     "modules/ethflow-watcher",
     "modules/example",
+    "modules/examples/price-alert",
     "modules/twap-monitor",
 ]
 resolver = "2"

modules/examples/price-alert/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "price-alert"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+description = "Shepherd example module: polls a Chainlink price oracle every block and emits a Warn log when the price crosses a config-supplied threshold."
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+shepherd-sdk = { path = "../../../crates/shepherd-sdk" }
+alloy-primitives = { version = "1.5", default-features = false, features = ["std"] }
+alloy-sol-types = { version = "1.5", default-features = false, features = ["std"] }
+wit-bindgen = { version = "0.57", default-features = false, features = ["macros", "realloc"] }

modules/examples/price-alert/module.toml

@@ -0,0 +1,43 @@
+# price-alert example module: polls a Chainlink price oracle on every
+# block and emits a Warn log when the price crosses a config-supplied
+# threshold. Demonstrates `chain::request` + ABI decode via
+# `alloy_sol_types` + config-driven module behaviour.
+
+[module]
+name = "price-alert"
+version = "0.1.0"
+# Placeholder content hash. 0.2 parses but does not verify this; 0.3
+# will compare against the sha256 of the loaded component bytes.
+component = "sha256:0000000000000000000000000000000000000000000000000000000000000000"
+
+[capabilities]
+required = ["logging", "chain"]
+optional = []
+
+[capabilities.http]
+# All chain traffic flows through the `chain` capability (host's
+# pinned alloy provider). No direct `http` calls.
+allow = []
+
+# --- subscriptions ----------------------------------------------------
+
+# New blocks on Sepolia drive the polling cadence.
+[[subscription]]
+kind = "block"
+chain_id = 11155111
+
+# --- config -----------------------------------------------------------
+
+[config]
+# Chainlink AggregatorV3Interface address. Default points at the
+# canonical ETH/USD feed on Sepolia.
+oracle_address = "0x694AA1769357215DE4FAC081bf1f309aDC325306"
+# Decimals the oracle reports (Chainlink USD pairs are 8).
+decimals = "8"
+# Threshold in the oracle's native decimal units.
+threshold = "2500.00"
+# "above" -> fires when answer >= threshold
+# "below" -> fires when answer <= threshold
+direction = "below"
+# Throttle: only poll every Nth block. Default 1.
+every_n_blocks = "1"