docs(openspec): archive fpagent-installer-multiarch and sync specs

Bundle selection is now architecture-aware, not just codename-aware, and the
no-compatible-bundle failure names the host architecture. Merged into the
fpagent-installer spec and archived the change.

openspec/changes/archive/2026-10-06-fpagent-installer-multiarch/tasks.md

@@ -0,0 +1,27 @@
+# Tasks
+
+- [x] 1. Hosted installer (`tools/public/fpagent/install.sh`): resolve the host
+  architecture from `uname -m` (`x86_64`/`i386`, else die) before any download,
+  and pass it to the asset picker. Verify: `bash -n install.sh`; a stubbed
+  `uname` printing `i686` reaches the metadata fetch, and one printing `aarch64`
+  dies without fetching.
+- [x] 2. Hosted installer: pick `-ubuntu-<codename>-<arch>.tar.gz` first, then
+  `-linux-<arch>.tar.gz`, and make the "no compatible bundle" message name the
+  host architecture. Verify: with a release offering only
+  `fpagent-<hash>-linux-i386.tar.gz`, a stubbed i686 host requests that asset;
+  with only `-linux-x86_64`, the same host fails and installs nothing.
+- [x] 3. Hosted installer: derive the version from the asset name for every
+  supported architecture (`linux-x86_64`, `linux-i386`,
+  `ubuntu-<codename>-x86_64`). Verify: an i386 asset name yields the git hash,
+  not an empty string.
+- [x] 4. Hosted installer: correct the help text — service and self-update are
+  on by default; list `--no-service`, `--no-updates`, `--update-base`, and keep
+  the note that options are forwarded to the bundle installer.
+  Verify: `install.sh --help` mentions the three flags and no longer implies
+  `--enable-service` is required.
+- [x] 5. Tests (`tools/test/fpagent-install.test.js`): stub `uname` on `PATH`
+  and assert i386 selection, cross-architecture rejection, and i386 version
+  parsing. Verify: `node --test tools/test/fpagent-install.test.js` passes.
+- [x] 6. Docs (`README.md`): installer section notes x86_64 and i386 bundles
+  and the on-by-default service/self-update. Verify: reading the section, no
+  flag claims contradict `install.sh --help`.