feat(shader): Add BlurPipeline class for frosted glass FBO setup

- Add BlurPipeline class with downsampled FBO support (scene, blur_a, blur_b)
- Implement 2-pass Gaussian blur shaders (horizontal + vertical)
- Add setup_fbos(), compile_blur_shaders(), prepare_blur(), cleanup() methods
- Add tests for BlurPipeline initialization, FBO setup, shader compilation, blur execution, and cleanup

Task: Phase 1, Task 1 of frosted_glass_20260313 track

.opencode/agents/tier2-tech-lead.md

@@ -1,7 +1,6 @@
 ---
 description: Tier 2 Tech Lead for architectural design and track execution with persistent memory
 mode: primary
-model: MiniMax-M2.5
 temperature: 0.4
 permission:
   edit: ask
@@ -14,9 +13,9 @@ ONLY output the requested text. No pleasantries.
 
 ## Context Management
 
-**MANUAL COMPACTION ONLY** — Never rely on automatic context summarization.
+**MANUAL COMPACTION ONLY** <EFBFBD> Never rely on automatic context summarization.
 Use `/compact` command explicitly when context needs reduction.
-You maintain PERSISTENT MEMORY throughout track execution — do NOT apply Context Amnesia to your own session.
+You maintain PERSISTENT MEMORY throughout track execution <EFBFBD> do NOT apply Context Amnesia to your own session.
 
 ## CRITICAL: MCP Tools Only (Native Tools Banned)
 
@@ -134,14 +133,14 @@ Before implementing:
 - Zero-assertion ban: Tests MUST have meaningful assertions
 - Delegate test creation to Tier 3 Worker via Task tool
 - Run tests and confirm they FAIL as expected
-- **CONFIRM FAILURE** — this is the Red phase
+- **CONFIRM FAILURE** <EFBFBD> this is the Red phase
 
 ### 3. Green Phase: Implement to Pass
 
 - **Pre-delegation checkpoint**: Stage current progress (`git add .`)
 - Delegate implementation to Tier 3 Worker via Task tool
 - Run tests and confirm they PASS
-- **CONFIRM PASS** — this is the Green phase
+- **CONFIRM PASS** <EFBFBD> this is the Green phase
 
 ### 4. Refactor Phase (Optional)