fix(cc-config): stop pinning CLAUDE_CONFIG_DIR in the bootstrap's plugin installer too

skill-plugins.js carried its own copy of the unconditional pin, with the
same comment claiming it keeps writes where cc-discovery reads. Same rule
as runClaude now: pin only when the operator set CLAUDE_HOME.

Also corrects three comments that described the old behaviour — the
confidently-wrong pair at these two call sites is what let two readers
believe reads and writes were aligned when they were not.

server/lib/cc-plugin-cli.js

@@ -17,8 +17,10 @@
  *     per argument kind.
  *   - Mutating calls are serialized in-process; two dashboard clicks must not
  *     interleave writes to the same manifest.
- *   - `CLAUDE_CONFIG_DIR` is pinned to the same CLAUDE_HOME the dashboard
- *     reads, so the CLI writes where `cc-discovery` looks.
+ *   - `CLAUDE_CONFIG_DIR` is pinned ONLY when the operator set `CLAUDE_HOME`.
+ *     Left unset it stays unset, because the CLI's own defaults already write
+ *     where `cc-discovery` looks — pinning it unconditionally is what once
+ *     made every MCP add/remove write a file nothing reads.
  *
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
@@ -138,11 +140,9 @@ function runClaude(args, opts = {}) {
     // function's own comment). Pinning CLAUDE_CONFIG_DIR unconditionally to
     // getClaudeHome() made the CLI write `~/.claude/.claude.json` instead —
     // a file nothing reads — so every default-install add/remove was inert.
-    // When CLAUDE_HOME IS set, this still pins it, but note the residual:
-    // cc-discovery's read stays pinned to $HOME/.claude.json regardless (see
-    // getClaudeJsonPath's comment) while the CLI then writes
-    // <CLAUDE_HOME>/.claude.json — a pre-existing split this task does not
-    // attempt to fix, since no install in this repo runs with CLAUDE_HOME set.
+    // When CLAUDE_HOME IS set, this pins it and the CLI writes
+    // <CLAUDE_HOME>/.claude.json — which is what getClaudeJsonPath() reads in
+    // that branch, so both cases line up. Keep the two in step.
     const env = { ...process.env };
     if (process.env.CLAUDE_HOME) env.CLAUDE_CONFIG_DIR = getClaudeHome();
     const child = execFile(