docs: three dangling links, and a gate so they cannot accumulate

The vault is the project's source of truth, so a link to a page that does not
exist is a promise the repo cannot keep. Three were dangling:

- Dankclaw/Gitea.md pointed twice at dankclaw/compose.yaml — **which this
  session retired**. The clean cutover obligation from my own change: the page
  now describes the unit that publishes 3000 and the canonical Caddy unit, and
  records why the compose file is gone.
- Dankclaw/Hermes-Dashboard.md linked [[LAN DNS]]; the page is [[LAN-DNS]].
- LLM/frank-medium-radiance-mxfp4.md linked [[Observability on Dankclaw]]; the
  page is [[Observability]].

scripts/check-vault-links.py + a seam keep it that way. The checker models
Obsidian's rules, which took three corrections to get right — and each was a
false positive that would have sent me editing healthy docs:

  1. Wikilinks are case-insensitive. A case-sensitive matcher reported 45
     breaks; 39 were `[[qBittorrent]]` vs qbittorrent.md.
  2. `[[folder/Note]]` resolves by path suffix, not by stem.
  3. `%20` in a markdown link is URL-encoding, not a filename.

Validating the linter against the resolver it models is the prerequisite for
trusting any of its output — the same discipline that caught a bad assertion of
my own earlier tonight.

scripts/check-vault-links.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+"""Report unresolved links in the docs vault (serverAppConfigs-docs).
+
+The vault is the project's source of truth, so a link to a page that does not
+exist is a promise the repo cannot keep. This models **Obsidian's** resolution
+rules rather than a naive one — three separate false-positive classes were found
+while writing it, and a linter that cries wolf is worse than no linter:
+
+  1. Wikilinks are **case-insensitive** (`[[qBittorrent]]` -> `qbittorrent.md`).
+     A case-sensitive matcher reported 45 breaks; 39 were this.
+  2. A path-qualified wikilink (`[[folder/Note]]`) resolves by **path suffix**,
+     not by stem, and must not be stem-matched. Treating the whole string as a
+     stem reported the PP pages as missing when they exist one directory down.
+  3. `%20` in a markdown link is URL-encoding. Dealing in raw text reported
+     `Network%20Architecture.md` as missing beside the real file.
+
+Exit status is 1 when any link is unresolved, so it gates a test.
+"""
+import pathlib
+import re
+import sys
+import urllib.parse
+
+WIKI = re.compile(r"\[\[([^\]\|#]+)(?:#[^\]\|]*)?(?:\|[^\]]*)?\]\]")
+MD = re.compile(r"(?<!\!)\[[^\]]*\]\(([^)]+)\)")
+EXTERNAL = ("http://", "https://", "mailto:", "#", "~")
+
+
+def strip_md(path: str) -> str:
+    return path[:-3] if path.endswith(".md") else path
+
+
+def build_index(vault: pathlib.Path):
+    pages = sorted(vault.rglob("*.md"))
+    stems: dict[str, list[pathlib.Path]] = {}
+    for page in pages:
+        stems.setdefault(page.stem.casefold(), []).append(page)
+    relative = [strip_md(str(p.relative_to(vault)).casefold()) for p in pages]
+    return pages, stems, relative
+
+
+def wiki_resolves(target: str, stems, relative) -> bool:
+    want = target.strip().rstrip("\\").casefold()
+    if "/" in want:
+        return any(r == want or r.endswith("/" + want) for r in relative)
+    return want in stems
+
+
+def md_resolves(base: pathlib.Path, target: str) -> bool:
+    text = urllib.parse.unquote(target.strip())
+    if text.startswith(EXTERNAL):
+        return True
+    text = text.split("#")[0].strip()
+    return not text or (base / text).exists()
+
+
+def main(argv: list[str]) -> int:
+    vault = pathlib.Path(argv[1] if len(argv) > 1 else "serverAppConfigs-docs")
+    pages, stems, relative = build_index(vault)
+    broken: list[str] = []
+    for page in pages:
+        text = page.read_text(errors="replace")
+        for target in WIKI.findall(text):
+            if not wiki_resolves(target, stems, relative):
+                broken.append(f"[wiki] {page.relative_to(vault)} -> {target.strip()}")
+        for target in MD.findall(text):
+            if not md_resolves(page.parent, target):
+                broken.append(f"[md]   {page.relative_to(vault)} -> {target.strip()}")
+    print(f"{len(pages)} pages, {len(broken)} unresolved links")
+    for line in broken:
+        print("  " + line)
+    return 1 if broken else 0
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv))