[dhruv1220]

Fixes #136.

Adding two sites whose folders share a name (e.g. two projects each with a platform folder) silently overwrote the first: the folder name becomes the site name, and Config.Upsert replaced the stored site by name, so only the second folder was ever served. The first site's path was lost with no warning.

Change (in internal/config/config.go):

• Upsert now refuses when a linked site with the same name already points at a different folder, with an error naming the existing path and the remedy: unlink it first if the project moved, or link the folder under a different name (flock link <name>). The guard compares paths after symlink resolution, so the same folder spelled two ways still re-links.
• Deliberately still allowed: re-linking the same folder with new settings, and linking over a parked directory with the same name (that is the promotion to a linked site; the parked folder stays parked and reappears if the link is removed).

Because the guard lives in Upsert, it covers every way a site is added: flock link, the GUI's add-site form (POST /v1/sites, which already surfaces Upsert errors as a 400), and the MCP site tools.

Tests:

• New TestUpsertRefusesSameNameForAnotherPath in internal/config/config_test.go: same folder re-links fine; a second folder under the same name fails with an error naming the first path, and the stored site is untouched. The test fails on the old code and passes with the fix. The first version of this guard also covered parked-discovered names, which broke the existing TestAllSitesMergesParkedAndLinkedSites promotion case — the guard now only fires for stored linked sites.
• go test ./internal/config/ ./internal/cli/ ./internal/api/ ./internal/mcpserver/ all green; gofmt and go vet clean.