build(opencode): bump bundled backend to 1.17.3+ide.0 (parent merge 1928d5a0c)

Rebuild from parent-repo merge commit 1928d5a0c, which merges upstream
opencode tag v1.17.3 (commit 8c8011336) into the fork's local merge branch
that carries 11 fork-only fixes on top of v1.17.1. Replaces stale
1.15.14+ide.0 bundle (May 2026 build).

Skipped versions: v1.16.0, v1.16.2, v1.17.0, v1.17.1, v1.17.2. Notable
upstream changes folded in:
- v1.17.x: subagent permissions (PR #31696), enterprise auth recovery
  (PR #31661), app device attachment picker (PR #31707), fff feature
  flag enablement, MCP timeouts/log notifications (PR #31618, #31752).
- v1.16.x: bedrock fixes, mantle openai support, openrouter sdk bump
  to 2.9.0, MCP SDK 1.29.0, fff filesystem search service unification.

Build pipeline this round (vs prior 1.15.14 bump):
- Backend: rebuilt via fork Makefile's vendor-opencode-backend-dev with
  OPENCODE_VERSION=0.0.0-build/v1.17.3-202606110938 exported from
  manifest builtFrom, so binary self-reports a clean build channel.
  sha256 b82861acebc0b9c44c43c6911574c9aceecd94de3fae4fd9e1e5fa92b7468efb
  (size 119,900,642 bytes, was 108,722,018 for 1.15.14).
- SPA: rebuilt via make vendor-spa for the first time since fork's
  initial SPA vendor. Chunk hashes shifted, many shiki language assets
  renamed; 60 deletions + 514 additions reflect natural Vite output
  churn rather than semantic change. index.html, oc-theme-preload.js
  carry the only structural diffs.

Integration surface unchanged: all 8 SSE event types, /session,
/session/status, /event HTTP routes still exposed; OPENCODE_DISABLE_CHANNEL_DB
guard left in place per fork commit 7ad72f2.

darwin-arm64 only; other platforms remain CI-filled (sha256: null in
manifest). Parent-repo merge branch and its 11 ahead commits intentionally
NOT pushed; backup at backup/pre-v1.17.3-merge-20260611-173303 in parent repo.

Tag: opencode-v1.17.3+ide.0

Author: cpkt9762

build/opencode-backend.json

@@ -1,15 +1,15 @@
 {
   "_comment": "Pinned opencode backend artifact for the IDE fork. See .sisyphus/plans/opencode-ide-fork-bundle-backend-plan.md (Step 3 / §4.6). Non-host sha256 entries are filled by CI runners on each target platform. The vendor-opencode-backend Makefile target validates that the host platform's binary at `src` matches `sha256` before copying into .vendored/.",
-  "version": "1.15.14+ide.0",
-  "commit": "dcb1546e5f567b3c6c2a018b0a3b0043e0d3ae69",
-  "commitShort": "dcb1546e5",
-  "builtFrom": "0.0.0-build/v1.15.14-202605311516",
-  "builtAt": "2026-05-31T08:53:15Z",
+  "version": "1.17.3+ide.0",
+  "commit": "1928d5a0c7f110f8a4d8a6ca4c3ce860b2a773d1",
+  "commitShort": "1928d5a0c",
+  "builtFrom": "0.0.0-build/v1.17.3-202606110938",
+  "builtAt": "2026-06-11T09:38:47Z",
   "platforms": {
     "darwin-arm64": {
       "src": "../packages/opencode/dist/opencode-darwin-arm64/bin/opencode",
-      "sha256": "e5da6bd597364ef9ed434f4d1f1e624c6d7d5c904ca91b43e512414229c45868",
-      "size": 108722018
+      "sha256": "b82861acebc0b9c44c43c6911574c9aceecd94de3fae4fd9e1e5fa92b7468efb",
+      "size": 119900642
     },
     "darwin-x64": {
       "src": "../packages/opencode/dist/opencode-darwin-x64/bin/opencode",