chore(root): sync oh-my-agent skills, hooks, and config migration

- Migrate oma-config.yaml to model_preset single-file format
- Add new skills: oma-image, oma-scholar, oma-skill-creator
- Update SKILL.md structure across all oma-* skills
- Expand keyword detection and triggers in hooks
- Sync agent definitions across claude/codex/cursor/gemini/qwen variants
- Add .agents/config/defaults.yaml

Author: gracefullight

.agents/agents/architecture-reviewer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-architecture.md` (orchestrated: `result-architecture-{sessionId}.md`)
 - Include: status, recommendation summary, tradeoffs, risks, validation steps, artifacts created
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY recommendations or structural edits, output this block:
@@ -29,6 +31,7 @@ CHARTER_CHECK:
 - LOW: proceed with assumptions
 - MEDIUM: list options, proceed with most likely
 - HIGH: set status blocked, list questions, DO NOT change architecture or code
+<!-- CHARTER_CHECK_END -->
 
 ## Rules
 

.agents/agents/backend-engineer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-backend.md` (orchestrated: `result-backend-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY code changes, output this block:
@@ -29,6 +31,7 @@ CHARTER_CHECK:
 - LOW: proceed with assumptions
 - MEDIUM: list options, proceed with most likely
 - HIGH: set status blocked, list questions, DO NOT write code
+<!-- CHARTER_CHECK_END -->
 
 ## Architecture
 

.agents/agents/db-engineer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-db.md` (orchestrated: `result-db-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY code changes, output this block:
@@ -25,6 +27,7 @@ CHARTER_CHECK:
 - Success criteria: {measurable criteria}
 - Assumptions: {defaults applied}
 ```
+<!-- CHARTER_CHECK_END -->
 
 ## Rules
 

.agents/agents/debug-investigator.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-debug.md` (orchestrated: `result-debug-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY code changes, output this block:
@@ -29,6 +31,7 @@ CHARTER_CHECK:
 - LOW: proceed with assumptions
 - MEDIUM: list options, proceed with most likely
 - HIGH: set status blocked, list questions, DO NOT write code
+<!-- CHARTER_CHECK_END -->
 
 ## Diagnosis Process
 

.agents/agents/frontend-engineer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-frontend.md` (orchestrated: `result-frontend-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY code changes, output this block:
@@ -25,6 +27,7 @@ CHARTER_CHECK:
 - Success criteria: {measurable criteria}
 - Assumptions: {defaults applied}
 ```
+<!-- CHARTER_CHECK_END -->
 
 ## Architecture
 

.agents/agents/mobile-engineer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-mobile.md` (orchestrated: `result-mobile-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY code changes, output this block:
@@ -25,6 +27,7 @@ CHARTER_CHECK:
 - Success criteria: {measurable criteria}
 - Assumptions: {defaults applied}
 ```
+<!-- CHARTER_CHECK_END -->
 
 ## Architecture
 

.agents/agents/pm-planner.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-pm.md` (orchestrated: `result-pm-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY planning work, output this block:
@@ -29,6 +31,7 @@ CHARTER_CHECK:
 - LOW: proceed with assumptions
 - MEDIUM: list options, proceed with most likely
 - HIGH: set status blocked, list questions, DO NOT proceed
+<!-- CHARTER_CHECK_END -->
 
 ## Planning Process
 

.agents/agents/qa-reviewer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-qa.md` (orchestrated: `result-qa-{sessionId}.md`)
 - Include: status, summary, files changed, acceptance criteria checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before starting review, output this block:
@@ -25,6 +27,7 @@ CHARTER_CHECK:
 - Must NOT do: modify source code, skip severity levels, report unverified findings
 - Success criteria: {all files reviewed, findings with file:line references}
 ```
+<!-- CHARTER_CHECK_END -->
 
 ## Review Priority Order
 

.agents/agents/tf-infra-engineer.md

@@ -13,6 +13,8 @@ Follow the vendor-specific execution protocol:
 - Write results to project root `.agents/results/result-tf-infra.md` (orchestrated: `result-tf-infra-{sessionId}.md`)
 - Include: status, summary, files changed, validation results, plan/apply notes, acceptance checklist
 
+<!-- CHARTER_CHECK_BEGIN -->
+
 ## Charter Preflight (MANDATORY)
 
 Before ANY infrastructure changes, output this block:
@@ -29,6 +31,7 @@ CHARTER_CHECK:
 - LOW: proceed with assumptions
 - MEDIUM: list options, proceed with most likely
 - HIGH: set status blocked, list questions, DO NOT apply destructive changes
+<!-- CHARTER_CHECK_END -->
 
 ## Rules
 

.agents/agents/variants/gemini.json

@@ -2,7 +2,7 @@
   "$schema": "./agent-variant.schema.json",
   "vendor": "gemini",
   "destDir": ".gemini/agents",
-  "modelDefault": "gemini-3-flash-preview",
+  "modelDefault": "gemini-3-flash",
   "toolsDefault": ["bash", "glob", "grep", "read", "edit", "write", "ask"],
   "protocolPath": ".agents/skills/_shared/runtime/execution-protocols/gemini.md",
   "agents": {