feat: add discovery timestamps to deviceInfo

[sinchubhat]

Add firstDiscovered (immutable) and rename lastUpdated to lastSynced.

Related to #1394

Depends on device-management-toolkit/console#1136

Description:

Field	When set	Mutable?
firstDiscovered	first discovery (discovered=true only)	no (write-once)
discovered	device creation	no (write-once)
lastSynced	every sync	yes (advances)

Note: lastUpdated is renamed to lastSynced; console maps the legacy lastUpdated on read so existing console keep working.

Observe the fields from the output:
discovered, firstDiscovered and lastSynced

Query from host

TOKEN=$(curl -sk https://localhost:8181/api/v1/authorize -H "Content-Type: application/json" -d '{"username":"<username>","password":"<password>"}' | jq -r '.token') && curl -sk https://localhost:8181/api/v1/devices -H "Authorization: Bearer $TOKEN" | jq '[.[] | {hostname, guid, deviceInfo}]'

Sync before activation:
discovered=true; firstDiscovered and lastSynced are equal:

sudo ./rpc amtinfo --sync --url https://<host_ip_addr>:8181/api/v1/devices \
  --auth-endpoint https://<host_ip_addr>:8181/api/v1/authorize \
  --auth-username <username> --auth-password "<password>" \
  --skip-cert-check --log-level=debug -v

Example:

"deviceInfo": {
  "discovered": true,
  "firstDiscovered": "2026-07-14T07:23:12Z",
  "lastSynced": "2026-07-14T07:23:12Z"
}

Activate directly:
discovered=false; firstDiscovered omitted; lastSynced set.
Use any one of below command:

sudo ./rpc activate --local --profile profile.yaml \
--key "<profile_key>" \
--skip-amt-cert-check --skip-cert-check \
--auth-endpoint "https://<host_ip_addr>:8181/api/v1/authorize" \
--auth-username <username> --auth-password "<password>" -v --log-level=debug

or

sudo ./rpc activate --url "https://<console-host>/api/v1/admin/profiles/export/<profile-name>?domainName=<domain-name>" --auth-username <username> --auth-password <password> --skip-amt-cert-check --skip-cert-check -v --log-level=debug

or

sudo ./rpc activate --profile <path-to-profile-file> --key <32-byte-key> --auth-endpoint https://<console-host>/api/v1/authorize --auth-username <username> --auth-password <password> --skip-amt-cert-check --log-level=debug -v --skip-cert-check

On later syncs: discovered and firstDiscovered stay unchanged (immutable); only lastSynced advances.
Full deactivation deletes the console record, so a later sync/activate creates a new record - firstDiscovered and discovered are set fresh:

sudo ./rpc deactivate --local --skip-amt-cert-check --skip-cert-check \
  --auth-endpoint "https://<host_ip_addr>:8181/api/v1/authorize" \
  --auth-username "<username>" \
  --auth-password "<password>" -v --log-level=debug

[Copilot]

Pull request overview

Adds discovery-related timestamp fields to the device sync payloads sent to Console, improving device lifecycle observability by distinguishing “first seen” vs “last sync” times and clarifying semantics via a field rename.

Changes:

• Introduces deviceInfo.firstDiscovered (write-once) and deviceInfo.lastSynced (advances each sync), replacing the prior deviceInfo.lastUpdated.
• Ensures lastSynced is stamped once per sync attempt and reused across the 404 auto-register POST + retry PATCH flow so timestamps agree.
• Adds test coverage validating timestamp behavior for existing devices and 404 auto-register scenarios for both discovered and explicitly provisioned devices.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
internal/device/api.go	Updates the shared DeviceInfo API shape to include firstDiscovered and rename lastUpdated → lastSynced.
internal/commands/amtinfo.go	Stamps and sends lastSynced on every sync; stamps firstDiscovered only on POST create when discovered=true; updates POST fallback to reuse the same sync timestamp.
internal/commands/amtinfo_test.go	Adds comprehensive tests asserting correct presence/absence and equality invariants for firstDiscovered / lastSynced across sync scenarios.