feat: add OpenProse plugin skills

extensions/open-prose/skills/prose/examples/19-advanced-parallel.prose

@@ -0,0 +1,71 @@
+# Advanced Parallel Execution (Tier 7)
+#
+# Demonstrates join strategies and failure policies
+# for parallel blocks.
+
+agent researcher:
+  model: haiku
+  prompt: "You are a research assistant. Provide concise information."
+
+# 1. Race Pattern: First to Complete Wins
+# ----------------------------------------
+# Use parallel ("first") when you want the fastest result
+# and don't need all branches to complete.
+
+parallel ("first"):
+  session: researcher
+    prompt: "Find information via approach A"
+  session: researcher
+    prompt: "Find information via approach B"
+  session: researcher
+    prompt: "Find information via approach C"
+
+session "Summarize: only the fastest approach completed"
+
+# 2. Any-N Pattern: Get Multiple Quick Results
+# --------------------------------------------
+# Use parallel ("any", count: N) when you need N results
+# but not necessarily all of them.
+
+parallel ("any", count: 2):
+  a = session "Generate a creative headline for a tech blog"
+  b = session "Generate a catchy headline for a tech blog"
+  c = session "Generate an engaging headline for a tech blog"
+  d = session "Generate a viral headline for a tech blog"
+
+session "Choose the best from the 2 headlines that finished first"
+  context: { a, b, c, d }
+
+# 3. Continue on Failure: Gather All Results
+# ------------------------------------------
+# Use on-fail: "continue" when you want all branches
+# to complete and handle failures afterwards.
+
+parallel (on-fail: "continue"):
+  session "Fetch data from primary API"
+  session "Fetch data from secondary API"
+  session "Fetch data from backup API"
+
+session "Combine all available data, noting any failures"
+
+# 4. Ignore Failures: Best-Effort Enrichment
+# ------------------------------------------
+# Use on-fail: "ignore" for optional enrichments
+# where failures shouldn't block progress.
+
+parallel (on-fail: "ignore"):
+  session "Get optional metadata enrichment 1"
+  session "Get optional metadata enrichment 2"
+  session "Get optional metadata enrichment 3"
+
+session "Continue with whatever enrichments succeeded"
+
+# 5. Combined: Race with Resilience
+# ---------------------------------
+# Combine join strategies with failure policies.
+
+parallel ("first", on-fail: "continue"):
+  session "Fast but might fail"
+  session "Slow but reliable"
+
+session "Got the first result, even if it was a handled failure"