fix: 13 skill review issues in /canvas

Critical:
- find precedence bug fixed: added \( -name '*.png' -o -name '*.jpg' \) grouping
  so -newer applies to BOTH extensions, not just .jpg
- Auto-positioning row y-detection: replaced broken right-half heuristic with
  min(n.y for all inside) — matches canvas-spec.md pseudocode
- WIKI.md canvas color table corrected: 1=red,2=orange,3=yellow,4=green,5=cyan,6=purple
  (was wrong mapping 1=blue etc from the graph CSS scheme, not canvas colors)

High:
- ID generation: full Unix timestamp (10 digits) instead of last-4-digits
  + added collision fallback (-2, -3 suffix)
- README: added /canvas add text and /canvas add pdf to commands table
- Aspect ratio: removed duplicate partial table from SKILL.md — now defers
  to canvas-spec.md as single source of truth
- new op: writes to wiki/overview.md not wiki/index.md (index has fixed schema)
- from banana: added explicit note that /banana is an optional external skill

Medium:
- add note: clarified 'type: file' vs 'type: link' — .md files use file nodes
- zone fallback y: changed from -140 (overlaps starter) to 280 (safe below all content)
- CLAUDE.md: added /save, /autoresearch, /canvas to Plugin Skills table

Low:
- allowed-tools: removed Grep (unused by any documented operation)
- Frontmatter: flattened description to single-line quoted string (fixes IDE
  YAML block scalar parsing diagnostic on lines 4-9)

.obsidian/graph.json

@@ -67,6 +67,6 @@
   "repelStrength": 20,
   "linkStrength": 1,
   "linkDistance": 80,
-  "scale": 0.6620854838064228,
+  "scale": 0.33684385915601145,
   "close": false
 }

.obsidian/workspace.json

@@ -11,10 +11,14 @@
             "id": "a31de1b302cdc5cf",
             "type": "leaf",
             "state": {
-              "type": "graph",
-              "state": {},
-              "icon": "lucide-git-fork",
-              "title": "Graph view"
+              "type": "markdown",
+              "state": {
+                "file": "CLAUDE.md",
+                "mode": "source",
+                "source": false
+              },
+              "icon": "lucide-file",
+              "title": "CLAUDE"
             }
           }
         ]
@@ -190,20 +194,20 @@
   },
   "active": "a31de1b302cdc5cf",
   "lastOpenFiles": [
-    "README.md.tmp.224546.1775557396282",
-    "README.md.tmp.224546.1775557389171",
-    "README.md.tmp.224546.1775557379648",
-    "skills/wiki/references/plugins.md.tmp.224546.1775557354797",
-    "skills/wiki/SKILL.md.tmp.224546.1775557343437",
+    "README.md.tmp.224546.1775557814794",
+    "CLAUDE.md.tmp.224546.1775557799570",
+    "WIKI.md.tmp.224546.1775557791066",
+    "skills/canvas/SKILL.md.tmp.224546.1775557782936",
+    "skills/canvas/SKILL.md.tmp.224546.1775557766591",
+    "skills/canvas/SKILL.md.tmp.224546.1775557704281",
+    "skills/canvas/SKILL.md.tmp.224546.1775557697284",
+    "skills/canvas/SKILL.md.tmp.224546.1775557686442",
+    "skills/canvas/SKILL.md.tmp.224546.1775557679632",
+    "skills/canvas/SKILL.md.tmp.224546.1775557667692",
+    "skills/canvas/SKILL.md.tmp.224546.1775557654636",
     "skills/canvas/references/canvas-spec.md",
-    "skills/canvas/references/canvas-spec.md.tmp.224546.1775557327401",
     "skills/canvas/SKILL.md",
-    "skills/canvas/SKILL.md.tmp.224546.1775557280886",
     "commands/canvas.md",
-    "commands/canvas.md.tmp.224546.1775557227716",
-    "wiki/canvases",
-    "skills/canvas/references",
-    "skills/canvas",
     "wiki/comparisons/Wiki vs RAG.md",
     "wiki/questions/How does the LLM Wiki pattern work.md",
     "wiki/meta/workflow-loop.gif",