docs: update branch references from master to main and OTP requirements to 26+

Author: GSMLG-BOT

.github/workflows/e2e-test.yml

@@ -5,9 +5,9 @@ name: E2E Tests
 
 on:
   push:
-    branches: [master, 'feature/**', '[0-9][0-9][0-9]-*']
+    branches: [main, 'feature/**', '[0-9][0-9][0-9]-*']
   pull_request:
-    branches: [master]
+    branches: [main]
   workflow_dispatch:  # Manual trigger
 
 jobs:

.github/workflows/lint.yml

@@ -3,10 +3,10 @@ name: Lint
 on:
   pull_request:
     branches:
-      - 'master'
+      - 'main'
   push:
     branches:
-      - 'master'
+      - 'main'
 
 jobs:
   lint:

.github/workflows/test.yml

@@ -3,10 +3,10 @@ name: Test
 on:
   pull_request:
     branches:
-      - 'master'
+      - 'main'
   push:
     branches:
-      - 'master'
+      - 'main'
 
 jobs:
   test:

.specify/memory/constitution.md

@@ -191,7 +191,7 @@ Security requirements below apply according to the operational mode in use.
 - Lint: OTP 23, 24, 25, 26, 27
 - Test: OTP 23, 25, 27 (subset for faster feedback)
 
-**MUST**: CI failures MUST block merging to master branch.
+**MUST**: CI failures MUST block merging to main branch.
 
 ## Performance Standards