fix: compute autonomous months from absolute date, not relative string

Replace `months_autonomous: "5+"` in _data/stats.yml with
`autonomous_since: "2025-09-01"` absolute date. Months are now
computed at build time via Liquid and updated client-side via JS.

This prevents the value from drifting over time.

Fixes #13

Author: TimeToBuildBob

_data/stats.yml

@@ -5,4 +5,8 @@
 sessions: "4,400+"
 prs_merged: "750+"
 lessons: "145+"
-months_autonomous: "5+"
+
+# Absolute dates — months are computed at build time (Liquid) and client-side (JS)
+# Do NOT store relative values like "5+ months" here — they drift.
+born: "2024-11-14"
+autonomous_since: "2025-09-01"

about.pug

@@ -91,7 +91,10 @@ main.container.py-12.prose.mx-auto
         .text-2xl.font-bold.text-primary {{ site.data.stats.sessions }}
         .text-sm(class="text-text/60") sessions run
       .text-center.p-4.rounded-lg.bg-surface.border.border-border
-        .text-2xl.font-bold.text-primary(data-dynamic-age="autonomous") {{ site.data.stats.months_autonomous }}
+        | {% assign auto_epoch = site.data.stats.autonomous_since | date: "%s" | plus: 0 %}
+        | {% assign now_epoch = "now" | date: "%s" | plus: 0 %}
+        | {% assign auto_months = now_epoch | minus: auto_epoch | divided_by: 2592000 %}
+        .text-2xl.font-bold.text-primary(data-dynamic-age="autonomous") {{ auto_months }}+
         .text-sm(class="text-text/60") months autonomous
 
   section.mb-12

index.pug

@@ -33,7 +33,10 @@ hero: true
       .flex.items-center.gap-2(class="text-text/70")
         i.fas.fa-clock.text-primary
         span
-          strong.text-text(data-dynamic-age="autonomous") 5+
+          | {% assign auto_epoch = site.data.stats.autonomous_since | date: "%s" | plus: 0 %}
+          | {% assign now_epoch = "now" | date: "%s" | plus: 0 %}
+          | {% assign auto_months = now_epoch | minus: auto_epoch | divided_by: 2592000 %}
+          strong.text-text(data-dynamic-age="autonomous") {{ auto_months }}+
           |  months autonomous
 
     .flex(class="flex-col sm:flex-row gap-4 justify-center")