implemented 06-watcher.md: non-blocking poll cycle enqueueing changed/new/auto-build branches via the async executor, startup recovery, retention/worktree pruning, JSON auto-build slot state, watcher.pollInterval config, and watcher health state

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/gittally/config/DurationParser.kt

@@ -2,18 +2,25 @@ package de.hoennig.gittally.config
 
 import java.time.Duration
 
-/** Parses durations in the `watcher.newBranchMaxAge` format: `5d` (days) or `12h` (hours). */
+/**
+ * Parses durations in the format used by `watcher.newBranchMaxAge` and `watcher.pollInterval`:
+ * `5d` (days), `12h` (hours), `10m` (minutes), or `30s` (seconds).
+ */
 object DurationParser {
-    private val pattern = Regex("""(\d+)([dh])""")
+    private val pattern = Regex("""(\d+)([dhms])""")
 
     fun parse(value: String): Duration {
         val match =
             pattern.matchEntire(value.trim())
-                ?: throw IllegalArgumentException("invalid duration '$value': expected <amount>d or <amount>h, e.g. 5d or 12h")
+                ?: throw IllegalArgumentException(
+                    "invalid duration '$value': expected <amount>d, <amount>h, <amount>m, or <amount>s, e.g. 5d or 10s",
+                )
         val (amount, unit) = match.destructured
         return when (unit) {
             "d" -> Duration.ofDays(amount.toLong())
-            else -> Duration.ofHours(amount.toLong())
+            "h" -> Duration.ofHours(amount.toLong())
+            "m" -> Duration.ofMinutes(amount.toLong())
+            else -> Duration.ofSeconds(amount.toLong())
         }
     }
 }

src/main/kotlin/de/hoennig/gittally/config/GitTallyConfig.kt

@@ -41,6 +41,8 @@ data class ArtifactsConfig(
 )
 
 data class WatcherConfig(
+    /** Delay between poll cycles, e.g. `10s` or `1m`. */
+    val pollInterval: String = "10s",
     val newBranchMaxAge: String = "5d",
 )