feat: read schedule,calendar and trend (#64)

## Summary
This PR ports schedule/calendar/trend read compatibility from the legacy
`node-bacstack` implementation into `@bacnet-js/client`, and adds read
examples for manual validation.

Source reference:
- https://github.com/EveGun/node-bacstack

## What changed
- Added specialized decode paths in `ReadProperty.decodeAcknowledge`
for:
  - `WEEKLY_SCHEDULE`
  - `EXCEPTION_SCHEDULE`
  - `EFFECTIVE_PERIOD`
  - `DATE_LIST`
- Added BACnet `WEEKNDAY` support in ASN.1 decode flow.
- Added `decodeRange` integration in `ReadRange.decodeAcknowledge`.
- Fixed non-zero offset slicing in `ReadRange` fallback range buffer
handling.
- Fixed closing-tag length consumption in exception schedule decode.
- Added unit tests for schedule/calendar parsing and trend range
decoding.
- Added read examples:
  - `examples/read-schedule-weekly.ts`
  - `examples/read-schedule-exceptions.ts`
  - `examples/read-schedule-period.ts`
  - `examples/read-calendar-datelist.ts`
  - `examples/read-trend.ts`

## Type consistency
- Trend range `timestamp` now returns `Date` (instead of epoch number)
for consistency with other decoded date/time fields.

## Validation
- `npm run lint` ✅
- `npm run test:unit` ✅
- Docker-based compliance tests executed successfully in local
environment ✅
- Manually validated against a WAGO PFC200 device
(schedule/calendar/trend read paths) ✅

## Notes
- Write examples were intentionally removed from this read-focused
branch.
- Write-side porting will follow in a separate branch/PR.
- Parser behavior was validated against real BACnet traffic captures
from WAGO PFC200 communication (Wireshark), then confirmed with live
device reads.

Author: EveGun

examples/read-calendar-datelist.ts

@@ -0,0 +1,31 @@
+import Bacnet, { ObjectType, PropertyIdentifier } from '../src'
+
+const target = process.argv[2] || '192.168.40.245'
+const instance = Number(process.argv[3] || 0)
+const port = Number(process.argv[4] || 47808)
+const address = { address: `${target}:${port}` }
+
+const client = new Bacnet({ apduTimeout: 4000 })
+
+client.on('error', (err: Error) => {
+	console.error(err)
+	client.close()
+})
+
+async function main() {
+	try {
+		const value = await client.readProperty(
+			address,
+			{ type: ObjectType.CALENDAR, instance },
+			PropertyIdentifier.DATE_LIST,
+		)
+		const entries = (value.values[0]?.value as any[]) || []
+		entries.forEach((entry) => console.log(entry))
+	} catch (err) {
+		console.error(err)
+	} finally {
+		client.close()
+	}
+}
+
+void main()

examples/read-schedule-exceptions.ts

@@ -0,0 +1,31 @@
+import Bacnet, { ObjectType, PropertyIdentifier } from '../src'
+
+const target = process.argv[2] || '192.168.40.245'
+const instance = Number(process.argv[3] || 0)
+const port = Number(process.argv[4] || 47808)
+const address = { address: `${target}:${port}` }
+
+const client = new Bacnet({ apduTimeout: 4000 })
+
+client.on('error', (err: Error) => {
+	console.error(err)
+	client.close()
+})
+
+async function main() {
+	try {
+		const value = await client.readProperty(
+			address,
+			{ type: ObjectType.SCHEDULE, instance },
+			PropertyIdentifier.EXCEPTION_SCHEDULE,
+		)
+		const specialEvents = (value.values[0]?.value as any[]) || []
+		specialEvents.forEach((entry) => console.log(entry))
+	} catch (err) {
+		console.error(err)
+	} finally {
+		client.close()
+	}
+}
+
+void main()

examples/read-schedule-period.ts

@@ -0,0 +1,30 @@
+import Bacnet, { ObjectType, PropertyIdentifier } from '../src'
+
+const target = process.argv[2] || '192.168.40.245'
+const instance = Number(process.argv[3] || 0)
+const port = Number(process.argv[4] || 47808)
+const address = { address: `${target}:${port}` }
+
+const client = new Bacnet({ apduTimeout: 4000 })
+
+client.on('error', (err: Error) => {
+	console.error(err)
+	client.close()
+})
+
+async function main() {
+	try {
+		const value = await client.readProperty(
+			address,
+			{ type: ObjectType.SCHEDULE, instance },
+			PropertyIdentifier.EFFECTIVE_PERIOD,
+		)
+		console.log(value.values[0]?.value || [])
+	} catch (err) {
+		console.error(err)
+	} finally {
+		client.close()
+	}
+}
+
+void main()

examples/read-schedule-weekly.ts

@@ -0,0 +1,39 @@
+import Bacnet, { ObjectType, PropertyIdentifier } from '../src'
+
+const target = process.argv[2] || '192.168.40.245:47808'
+const instance = Number(process.argv[3] || 0)
+const localPortArg = process.argv[4]
+const address = {
+	address: target.includes(':') ? target : `${target}:47808`,
+}
+
+const client = new Bacnet(
+	localPortArg
+		? { apduTimeout: 4000, port: Number(localPortArg) }
+		: { apduTimeout: 4000 },
+)
+
+client.on('error', (err: Error) => {
+	console.error(err)
+	client.close()
+})
+
+async function main() {
+	try {
+		const value = await client.readProperty(
+			address,
+			{ type: ObjectType.SCHEDULE, instance },
+			PropertyIdentifier.WEEKLY_SCHEDULE,
+		)
+		const weekly = (value.values[0]?.value as any[]) || []
+		weekly.forEach((day, index) => {
+			console.log(`day ${index}:`, day)
+		})
+	} catch (err) {
+		console.error(err)
+	} finally {
+		client.close()
+	}
+}
+
+void main()

examples/read-trend.ts

@@ -0,0 +1,52 @@
+import Bacnet, {
+	MaxSegmentsAccepted,
+	ObjectType,
+	PropertyIdentifier,
+} from '../src'
+
+const target = process.argv[2] || '192.168.40.245'
+const instance = Number(process.argv[3] || 0)
+const startIndex = Number(process.argv[4] || 1)
+const count = Number(process.argv[5] || 55)
+const port = Number(process.argv[6] || 47808)
+const address = { address: `${target}:${port}` }
+
+const client = new Bacnet({ apduTimeout: 10000 })
+
+client.on('error', (err: Error) => {
+	console.error(err)
+	client.close()
+})
+
+async function main() {
+	try {
+		const recordCount = await client.readProperty(
+			address,
+			{ type: ObjectType.TREND_LOG, instance },
+			PropertyIdentifier.RECORD_COUNT,
+		)
+		console.log('recordCount:', recordCount.values?.[0]?.value)
+
+		const response = await client.readRange(
+			address,
+			{ type: ObjectType.TREND_LOG, instance },
+			startIndex,
+			count,
+			{ maxSegments: MaxSegmentsAccepted.SEGMENTS_65 },
+		)
+
+		// Until readRange typed trend decoding is ported, inspect raw payload.
+		if ((response as any).values) {
+			console.log((response as any).values)
+		} else {
+			console.log(response)
+			console.log(response.rangeBuffer)
+		}
+	} catch (err) {
+		console.error(err)
+	} finally {
+		client.close()
+	}
+}
+
+void main()