Add config validation and dashboard

Add YAML config loading with validation, env overrides for secrets, and
a web dashboard exposing health, stats, and recent events.

sources/event.v

@@ -0,0 +1,111 @@
+module sources
+
+pub struct Event {
+pub mut:
+	source   string
+	name     string
+	topic    string
+	priority int
+	tags     []string
+	message  string
+	raw      string
+}
+
+pub fn (e Event) clone() Event {
+	return Event{
+		source:   e.source
+		name:     e.name
+		topic:    e.topic
+		priority: e.priority
+		tags:     e.tags.clone()
+		message:  e.message
+		raw:      e.raw
+	}
+}
+
+pub struct GiteaSource {
+pub mut:
+	name         string         @[json: 'name']
+	webhook_path string         @[json: 'webhook_path']
+	topic        string         @[json: 'topic']
+	template     string         @[json: 'template']
+	priority_map map[string]int @[json: 'priority_map']
+	tags         []string       @[json: 'tags']
+	repo         string         @[json: 'repo']
+}
+
+pub struct UptimeKumaState {
+pub mut:
+	priority int      @[json: 'priority']
+	tags     []string @[json: 'tags']
+}
+
+pub struct UptimeKumaSource {
+pub mut:
+	name         string                     @[json: 'name']
+	webhook_path string                     @[json: 'webhook_path']
+	topic        string                     @[json: 'topic']
+	template     string                     @[json: 'template']
+	priority_map map[string]int             @[json: 'priority_map']
+	tags         []string                   @[json: 'tags']
+	state_map    map[string]UptimeKumaState @[json: 'state_map']
+}
+
+pub struct DockerSource {
+pub mut:
+	name         string         @[json: 'name']
+	topic        string         @[json: 'topic']
+	template     string         @[json: 'template']
+	priority_map map[string]int @[json: 'priority_map']
+	tags         []string       @[json: 'tags']
+	hosts        []string       @[json: 'hosts']
+	events       []string       @[json: 'events']
+}
+
+pub struct HttpCheck {
+pub mut:
+	url           string @[json: 'url']
+	topic         string @[json: 'topic']
+	priority      int    @[json: 'priority']
+	expect_status int    @[json: 'expect_status']
+	timeout       int    @[json: 'timeout']
+	template      string @[json: 'template']
+}
+
+pub struct HttpPollSource {
+pub mut:
+	name     string      @[json: 'name']
+	interval int         @[json: 'interval']
+	checks   []HttpCheck @[json: 'checks']
+}
+
+pub struct CronSource {
+pub mut:
+	name         string         @[json: 'name']
+	webhook_path string         @[json: 'webhook_path']
+	topic        string         @[json: 'topic']
+	template     string         @[json: 'template']
+	priority_map map[string]int @[json: 'priority_map']
+	tags         []string       @[json: 'tags']
+}
+
+pub struct GenericSource {
+pub mut:
+	name         string         @[json: 'name']
+	webhook_path string         @[json: 'webhook_path']
+	topic        string         @[json: 'topic']
+	template     string         @[json: 'template']
+	priority_map map[string]int @[json: 'priority_map']
+	tags         []string       @[json: 'tags']
+}
+
+// render_source_template applies variable substitution to a template string.
+// Placeholders are {varname}. Shared by all source transformers in this module.
+pub fn render_source_template(template string, vars map[string]string) string {
+	mut result := template.clone()
+	for key, value in vars {
+		placeholder := '{${key}}'
+		result = result.replace(placeholder, value)
+	}
+	return result
+}