Rename project esp+sensair -> esp-sensair; publish fabrication files as release assets

- Rename KiCad project/schematic/board (and local .prl) to drop the '+',
  updating all internal cross-references (project name, sheetfile, title blocks)
- Remove the '+' from Gerber/drill/job filenames and the job file's internal
  Name/Path references; rebuild the upload zip with clean names
- Stop tracking gerber/ (derived artifacts): untrack, gitignore, and publish
  the fabrication zip as a GitHub Release asset instead
- README/CHANGELOG: point fabrication data at the release, mark the '+' naming
  issue as fixed, refresh the repository layout

.gitignore

@@ -15,7 +15,10 @@ _restore_backup_*/
 netlist/
 reports/
 
-# Generated fabrication outputs are published in gerber/ ; keep ad-hoc exports out
+# Fabrication outputs (Gerbers, drills, job file, upload zip) are derived
+# artifacts published as GitHub Release assets, not committed to the tree.
+# Regenerate from KiCad and attach the zip to the matching release tag.
+gerber/
 *.gbr.bak
 *.drl.bak