feat(settings): configurable monitoring thresholds

Move the hardcoded warn/crit cutoffs into Settings -> Thresholds (DB-backed,
live, no restart). New thresholds.* keys + to_thresholds_cfg() + a
threshold_style(value, kind) jinja global that reads them; latency reuses the
existing ping good/warn keys, uptime is direction-aware (floors).

Replace the _macros metric_style/uptime_style macros (now removed) with the
global across Hosts-Overview, host_agent fleet + panel, Uptime/SLA widget, and
the ping page uptime column — all now honor the configured cutoffs. Uptime keeps
its green 'good' look when not degraded.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

steward/core/settings.py

@@ -68,6 +68,16 @@ DEFAULTS: dict[str, Any] = {
     "ansible.max_concurrent_runs": 3,
     "ping.threshold.good_ms": 50,
     "ping.threshold.warn_ms": 200,
+    # Degraded/critical cutoffs for metric coloring (warn=amber, crit=red).
+    # cpu/mem/disk/load are percentages (load is load-per-core %); temp in °C.
+    # uptime is "higher is better" so its warn/crit are floors. Ping latency
+    # reuses ping.threshold.good_ms/warn_ms above.
+    "thresholds.cpu_warn": 80, "thresholds.cpu_crit": 90,
+    "thresholds.mem_warn": 80, "thresholds.mem_crit": 90,
+    "thresholds.disk_warn": 80, "thresholds.disk_crit": 90,
+    "thresholds.load_warn": 80, "thresholds.load_crit": 100,
+    "thresholds.temp_warn": 70, "thresholds.temp_crit": 85,
+    "thresholds.uptime_warn": 99.0, "thresholds.uptime_crit": 95.0,
     "plugins.index_url": "https://git.fabledsword.com/bvandeusen/Steward-plugins/raw/branch/main/index.yaml",
     # Default-enabled plugins. These are the generic, non-vendor-specific
     # bundled plugins (protocols/standards, not a single product) — useful on
@@ -224,6 +234,53 @@ def to_ldap_cfg(settings: dict[str, Any]) -> dict:
     return {k[len("ldap."):]: settings.get(k, DEFAULTS[k]) for k in DEFAULTS if k.startswith("ldap.")}
 
 
+def to_thresholds_cfg(settings: dict[str, Any]) -> dict:
+    """Per-metric (warn, crit, direction) policy for degraded-value coloring.
+
+    Centralizes "what counts as degraded" so templates just name a metric kind
+    via the threshold_style() jinja global. `dir` is "high" (higher is worse,
+    e.g. CPU) or "low" (lower is worse, e.g. uptime %). Latency reuses the
+    existing ping good/warn thresholds.
+    """
+    g = settings.get
+    return {
+        "cpu":     {"warn": g("thresholds.cpu_warn", 80),  "crit": g("thresholds.cpu_crit", 90),  "dir": "high"},
+        "mem":     {"warn": g("thresholds.mem_warn", 80),  "crit": g("thresholds.mem_crit", 90),  "dir": "high"},
+        "disk":    {"warn": g("thresholds.disk_warn", 80), "crit": g("thresholds.disk_crit", 90), "dir": "high"},
+        "load":    {"warn": g("thresholds.load_warn", 80), "crit": g("thresholds.load_crit", 100), "dir": "high"},
+        "temp":    {"warn": g("thresholds.temp_warn", 70), "crit": g("thresholds.temp_crit", 85), "dir": "high"},
+        "latency": {"warn": g("ping.threshold.good_ms", 50), "crit": g("ping.threshold.warn_ms", 200), "dir": "high"},
+        "uptime":  {"warn": g("thresholds.uptime_warn", 99.0), "crit": g("thresholds.uptime_crit", 95.0), "dir": "low"},
+    }
+
+
+def threshold_style_for(value: Any, kind: str, thresholds: dict) -> str:
+    """Return an inline-style fragment (amber at warn, red at crit) for a metric.
+
+    The Python twin of the old _macros.metric_style, but reading configurable
+    cutoffs from `thresholds` (see to_thresholds_cfg) and handling both
+    directions. Empty string when normal/unknown/None — drop straight into a
+    span's style="".
+    """
+    if value is None:
+        return ""
+    th = thresholds.get(kind)
+    if not th:
+        return ""
+    warn, crit, direction = th["warn"], th["crit"], th.get("dir", "high")
+    if direction == "low":
+        if value < crit:
+            return "color:var(--red);font-weight:700;"
+        if value < warn:
+            return "color:var(--yellow);font-weight:600;"
+    else:
+        if value >= crit:
+            return "color:var(--red);font-weight:700;"
+        if value >= warn:
+            return "color:var(--yellow);font-weight:600;"
+    return ""
+
+
 def to_plugins_cfg(settings: dict[str, Any]) -> dict:
     """Assemble {plugin_name: {...config}} from all plugin.* keys."""
     result = {}