feat(telemetry): report process memory and process and host uptime

docs/roadmap.md

@@ -55,7 +55,8 @@ or current fleet size. Metric labels should remain bounded; no per-device labels
 
 ## Process And Host Visibility
 
-- [ ] Add shared process measurements for agent and CC: start time/uptime, resident memory, CPU time, and open file descriptors where supported. Keep version as resource metadata rather than repeating it on every sample.
+- [x] Add Linux process age/RSS and host uptime gauges for agent and CC through opt-in OTLP, using the existing collection interval. Core owns OS-independent instruments; wakey-linux supplies the optional procfs reader. Missing data omits observations; no added labels, config fields, health routes or polling tasks. Collector coverage verifies units and values; router/live dashboard validation pending.
+- [ ] Extend process measurements with CPU time and open file descriptors where supported, plus start-time/version metadata if needed. Keep version as resource metadata rather than repeating it on every sample.
 - [ ] Add a small host summary: hostname, OS/kernel, CPU count, host uptime, load, and available/total memory. Distinguish host uptime from process uptime so router reboots and agent restarts are visible separately. Sources must tolerate missing Linux files; not every agent host is a router.
 - [ ] Expose changing measurements through OTLP on a modest sampling interval; show selected process/host details on Fleet Health and agent details. Keep host information behind the protected operator interface, not public health endpoints. Avoid expensive reads on every request and unbounded labels.
 - [ ] Keep `/healthz` as cheap liveness; consider a separate bounded `/readyz` database-access check for CC. Collector outages and disconnected fleet agents must not make a functioning CC unready.

docs/telemetry-recipes.md

@@ -26,6 +26,41 @@ that includes recent activity and allow at least two exports for rate queries.
 Counter resets on restart are handled by `rate` and `increase`. Apply those
 functions **before** summing across instances so individual resets remain visible.
 
+## Process And Host
+
+Discover the new gauges first (these are Linux-only):
+
+```promql
+count by (__name__, job, instance) ({__name__=~"wakey_(process|host)_.*"})
+```
+
+Process age and host uptime, in seconds:
+
+```promql
+wakey_process_uptime_seconds
+```
+
+```promql
+wakey_host_uptime_seconds
+```
+
+Set Grafana's unit to a duration. Compare the two: process age resetting while
+host uptime continues suggests a daemon restart; both resetting suggests a host
+restart or a changed namespace/view. Missing samples are not a zero uptime or
+proof of a restart. These are gauges: do not use `rate` or `increase` on them.
+
+Resident process memory, in bytes:
+
+```promql
+wakey_process_memory_resident_bytes
+```
+
+Set the unit to **bytes (IEC)**. Keep `job` and `instance` in the legend to compare
+agent and CC separately. RSS includes shared/file-backed pages and is not heap
+allocation alone. A missing series can mean disabled telemetry, an unsupported
+platform, unavailable procfs, or export trouble. No new health endpoint or host
+inventory is provided here; do not sum host uptime from multiple daemons.
+
 ## Operations
 
 Completed attempts per second, including errors and timeouts:

docs/telemetry.md

@@ -157,6 +157,9 @@ queries, rates, averages, percentiles, and Grafana units.
 | `wakey.stored.devices` | CC gauge of retained device rows, labeled by `agent_id` |
 | `wakey.stored.endpoints` | CC gauge of retained endpoint rows, including inactive entries, labeled by `agent_id` |
 | `wakey.fleet.devices` | CC gauge of unfiltered grouped identities, labeled by `identity` (`saved` or `unsaved`) |
+| `wakey.process.uptime` | Linux gauge: seconds since this process's kernel-reported start, including suspend |
+| `wakey.process.memory.resident` | Linux gauge: approximate resident memory in bytes, from VmRSS |
+| `wakey.host.uptime` | Linux gauge: uptime in seconds reported by the process's procfs view, including suspend |
 | `wakey.terminal.active` | Agent PTY workers currently alive |
 | `wakey.terminal.input.bytes` | Input bytes received by the terminal relay |
 | `wakey.terminal.output.bytes` | Output bytes read from the PTY, including while detached |
@@ -164,9 +167,30 @@ queries, rates, averages, percentiles, and Grafana units.
 
 Metric labels do not include request/session IDs, MACs, or IPs. New spans use
 `skip_all` and explicitly select safe fields; terminal bytes and credentials are
-not attached. Profiles, host CPU/RSS metrics, connected-agent gauges, and export-loss
+not attached. Profiles, host CPU/total-memory metrics, connected-agent gauges, and export-loss
 dashboards are not part of this initial slice.
 
+Process and host gauges are registered automatically for Linux agent/CC daemons
+when OTLP is enabled. `wakey-core` owns the OS-independent instruments and
+`ProcessMetricsSource` interface; `wakey-linux` supplies the procfs reader via
+its optional `telemetry` feature. Each daemon attaches that reader to its
+telemetry guard, so core has no Linux dependency or filesystem reads.
+Their small procfs reads run during the existing 30-second
+metric collection and final shutdown collection; no independent poller or task
+is started. Non-Linux builds omit these gauges. Missing/unreadable procfs data
+omits the affected observation instead of reporting zero or failing the daemon.
+No hostname, PID, command line or environment values are exported by this slice.
+Service/instance resource attributes identify each daemon; two daemons on the
+same host can report the same host uptime, so do not sum it across processes.
+
+RSS includes anonymous, file-backed and shared resident pages, not just heap,
+and is an approximate kernel measurement. Process age uses procfs start ticks
+and uptime, not wall-clock subtraction or telemetry initialization time.
+Container/time namespaces can change the visible host clock; this is the
+process's Linux view, not an assertion about a physical machine's boot time.
+The Linux parser is [procfs](https://docs.rs/procfs/0.18.0/procfs/), with optional
+default features disabled. Public `/healthz` remains unchanged.
+
 Current-state fleet gauges sample independently every 30 seconds, with bounded
 revision retries to avoid mixed-state counts. Enrolled empty agents report zero;
 removed labels disappear when no enrollment or retained rows remain. Failed samples