feat(agent): integrate skill discovery into Dream consolidation

Instead of a separate skill discovery system, extend Dream's two-phase
pipeline to also detect reusable behavioral patterns from conversation
history and generate SKILL.md files.

Phase 1 gains a [SKILL] output type for pattern detection.
Phase 2 gains write_file (scoped to skills/) and read access to builtin
skills, enabling it to check for duplicates and follow skill-creator's
format conventions before creating new skills.

Inspired by PR #3039 by @wanghesong2019.

Co-authored-by: wanghesong2019 <wanghesong2019@users.noreply.github.com>

nanobot/templates/agent/dream_phase1.md

@@ -3,6 +3,7 @@ Compare conversation history against current memory files. Also scan memory file
 Output one line per finding:
 [FILE] atomic fact (not already in memory)
 [FILE-REMOVE] reason for removal
+[SKILL] kebab-case-name: one-line description of the reusable pattern
 
 Files: USER (identity, preferences), SOUL (bot behavior, tone), MEMORY (knowledge, project context)
 
@@ -18,6 +19,12 @@ Staleness — flag for [FILE-REMOVE]:
 - Detailed incident info after 14 days — reduce to one-line summary
 - Superseded: approaches replaced by newer solutions, deprecated dependencies
 
+Skill discovery — flag [SKILL] when ALL of these are true:
+- A specific, repeatable workflow appeared 2+ times in the conversation history
+- It involves clear steps (not vague preferences like "likes concise answers")
+- It is substantial enough to warrant its own instruction set (not trivial like "read a file")
+- Do not worry about duplicates — the next phase will check against existing skills
+
 Do not add: current weather, transient status, temporary errors, conversational filler.
 
 [SKIP] if nothing needs updating.

nanobot/templates/agent/dream_phase2.md

@@ -1,11 +1,13 @@
 Update memory files based on the analysis below.
 - [FILE] entries: add the described content to the appropriate file
 - [FILE-REMOVE] entries: delete the corresponding content from memory files
+- [SKILL] entries: create a new skill under skills/<name>/SKILL.md using write_file
 
 ## File paths (relative to workspace root)
 - SOUL.md
 - USER.md
 - memory/MEMORY.md
+- skills/<name>/SKILL.md (for [SKILL] entries only)
 
 Do NOT guess paths.
 
@@ -17,6 +19,17 @@ Do NOT guess paths.
 - Surgical edits only — never rewrite entire files
 - If nothing to update, stop without calling tools
 
+## Skill creation rules (for [SKILL] entries)
+- Use write_file to create skills/<name>/SKILL.md
+- Before writing, read_file skills/skill-creator/SKILL.md for format reference (frontmatter structure, naming conventions, quality standards)
+- **Dedup check**: read existing skills listed below to verify the new skill is not functionally redundant. Skip creation if an existing skill already covers the same workflow.
+- Include YAML frontmatter with name and description fields
+- Keep SKILL.md under 2000 words — concise and actionable
+- Include: when to use, steps, output format, at least one example
+- Do NOT overwrite existing skills — skip if the skill directory already exists
+- Reference specific tools the agent has access to (read_file, write_file, exec, web_search, etc.)
+- Skills are instruction sets, not code — do not include implementation code
+
 ## Quality
 - Every line must carry standalone value
 - Concise bullets under clear headers