feat(config): Phase 2 Configurable Output — vestige.toml + output profiles (v2.1.26)

Rebased on v2.1.25 merge/supersede and bumped the post-release metadata to v2.1.26 so this branch does not roll versions backward.

Adds local vestige.toml defaults, output profiles, and MCP response precedence for search, timeline, codebase context, and session context.

Verified:
- cargo metadata --format-version 1 --locked --no-deps
- cargo test -p vestige-core config --no-fail-fast
- cargo test -p vestige-mcp config --no-fail-fast

server.json

@@ -7,12 +7,12 @@
     "url": "https://github.com/samvallad33/vestige",
     "source": "github"
   },
-  "version": "2.1.25",
+  "version": "2.1.26",
   "packages": [
     {
       "registryType": "npm",
       "identifier": "vestige-mcp-server",
-      "version": "2.1.25",
+      "version": "2.1.26",
       "transport": {
         "type": "stdio"
       }