docs: end-to-end gardening — links, stale refs, tailscale.md update

Comprehensive documentation gardening across the merged repo:

- tailscale.md: fully rewritten with current ground truth. The netinfra
  pair now runs production Technitium with all knel.net records
  replicated. Both LAN IPs resolve knel.net device names and recurse
  externally. The old "NXDOMAIN / zone is stale" findings are replaced
  with the resolved state and current recommendations.
- AGENTS.md: rewritten with Gitea-compatible clickable relative links
  to all key scripts and docs. Autonomous commit/push policy
  prominently documented. SSH user corrected to localuser.
- README.md: directory table and docs table now use clickable links.
- All .md cross-references converted to Gitea-renderable relative links.
- Stale path references (ProjectCode/, Project-Tests/, ProjectDocs/)
  updated to current names (provisioning/, tests/) across all docs.
- Stale repo name "FetchApply" / "KNELServerBuild" updated to
  "PFVCluster" in actionable docs; historical AI-review docs tagged
  with an HTML comment notice.
- REFACTORING-EXAMPLES.md: tagged as historical (pre-refactor patterns).
- tests/README.md, dns-cluster-setup/README.md, docs/DEPLOYMENT.md,
  docs/SECURITY.md: path references fixed to current structure.

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docs/PROJECT.md

@@ -391,7 +391,7 @@ be on tsys5:
 **Simplest path:** migrate cnode3 and cnode4 storage to tsys5 (S3 and S2) via
 PDM. Then tsys4 failure leaves cnode5 + cnode3 + cnode4 = 3 of 5 = quorum OK.
 
-### 5.5 Future k8s architecture (next session -- see K8S.md)
+### 5.5 Future k8s architecture (next session -- see [K8S.md](K8S.md))
 
 The k8s layer will be tackled soon. Key requirements from user:
 
@@ -606,7 +606,7 @@ PCIe NIC would eliminate this risk (same recommendation as tsys4).
 tsys6 to tsys7 storage path now measures **1.83 Gbps** (was 943 Mbps).
 The switch LACP hash change took effect after renegotiation. The 56-106K
 retransmits on this path are confirmed to be non-lossy multi-flow TCP-over-
-LACP overhead. See `RESULTS.md` for the full analysis.
+LACP overhead. See `RESULTS.md` (not yet created) for the full analysis.
 
 ### 9.4 NFS nconnect=4 + noatime confirmed active
 
@@ -819,7 +819,7 @@ This belongs in the next budget cycle.
 3. Run `scripts/check.sh` on tsys2 once Proxmox is loaded.
 4. Update PROJECT.md with post-hardware numbers.
 
-### 12.4 Future: Kubernetes deep-dive (see K8S.md)
+### 12.4 Future: Kubernetes deep-dive (see [K8S.md](K8S.md))
 
 Next major workstream. Requirements captured:
 - **vcluster + Rancher** for multi-tenant k8s management