Normalize multi-word tags to kebab-case

"subresource integrity", "task scheduler", and "conventional commits"
had spaces, producing broken-looking /tags/<tag>/ URLs. Also fixes a
silent bug: site.config.ts's tagDescriptions already keyed
"subresource-integrity" with a hyphen, so the per-tag description
never actually matched the un-normalized tag.

Added normalizeTag() to migrate-posts-to-writings.mjs so re-running
the migration script doesn't reintroduce the spaces from the
untouched content/posts/ originals.

content/writings/obsidian-sync/index.md

@@ -6,7 +6,7 @@ date = 2023-10-01
 draft = false
 
 [taxonomies]
-tags = [ "obsidian", "git", "sync", "windows", "cron", "task scheduler", "powershell" ]
+tags = [ "obsidian", "git", "sync", "windows", "cron", "task-scheduler", "powershell" ]
 
 +++
 

content/writings/semantic-version-and-conventional-commits/index.md

@@ -6,7 +6,7 @@ date = 2023-01-24
 draft = false
 
 [taxonomies]
-tags = [ "git", "semver", "workflow", "conventional commits" ]
+tags = [ "git", "semver", "workflow", "conventional-commits" ]
 
 +++
 

content/writings/subresource-integrity/index.md

@@ -6,7 +6,7 @@ date = 2023-04-29
 draft = false
 
 [taxonomies]
-tags = [ "subresource integrity", "csp", "cors" ]
+tags = [ "subresource-integrity", "csp", "cors" ]
 
 +++