refactor(prompts): clarified agent and system guidance

- Standardized prompt format, removing XML-like tags.
- Emphasized RFC 2119 keywords using bolding across all prompts.
- Rewrote the core system prompt with enhanced structure and directives.

packages/coding-agent/src/commit/agentic/prompts/system.md

@@ -13,11 +13,11 @@ Workflow rules:
 6. Do not use read.
 
 Commit requirements:
-- Summary line: past-tense verb, <= 72 chars, no trailing period.
+- Summary line: past-tense verb, ≤ 72 chars, no trailing period.
 - Avoid filler words: comprehensive, various, several, improved, enhanced, better.
 - Avoid meta phrases: "this commit", "this change", "updated code", "modified files".
 - Scope: lowercase, max two segments; only letters, digits, hyphens, underscores.
-- Detail lines optional (0-6). Each sentence ending in period, <= 120 chars.
+- Detail lines optional (0-6). Each sentence ending in period, ≤ 120 chars.
 
 Conventional commit types:
 {{types_description}}

packages/coding-agent/src/commit/prompts/reduce-system.md

@@ -10,7 +10,7 @@ Determine:
 4. CHANGELOG: Metadata for user-visible changes
 </instructions>
 <scope-rules>
-- Component name if >=60% changes target it
+- Component name if ≥60% changes target it
 - null if spread across multiple components
 - scope_candidates as primary source
 - Valid: specific component names (api, parser, config, etc.)