feat: consolidate spec docs, improve discovery flow, add feature derivation

[nullhack]

Summary

• Consolidate spec docs: merge event_storming, context_map, technical_design templates into domain_model and product_definition templates
• Add Events/Commands and Context Map sections to domain_model.md.template
• Add Technology Stack and Dependencies sections to product_definition.md.template
• Delete document-dependencies.yaml (unused)

Discovery Flow (v7 to v11)

• Merge event-storming + language-definition + domain-modeling states into single domain-discovery state with 3 skills: facilitate-event-storming, domain-discovery, define-ubiquitous-language
• Split feature-discovery into 2 skills: discover-features (boundary identification) and discover-rules (rule derivation)
• Add features/*.feature to feature-discovery inputs

Architecture Flow (v7 to v8)

• Merge adr-draft into technical-design state (skills: design-technical-solution, draft-adr)

New Knowledge Files

• domain-modeling/domain-modeling.md — Formalization knowledge (bounded contexts, entities, relationships, aggregates)
• requirements/feature-boundaries.md — Feature boundary derivation from delivery order, context alignment, splitting criteria
• requirements/rule-derivation.md — Systematic rule derivation from events, invariants, commands, quality attributes

Enriched Knowledge Files

• domain-modeling/event-storming.md — Brandolini 6 phases, extraction heuristics, hotspot detection
• requirements/ubiquitous-language.md — Term detection heuristics, cross-referencing procedures
• requirements/feature-discovery.md — Content section with discovery sequence and gap analysis
• skill-design/principles.md — "read on demand" to "read all before starting work"

Skill Improvements

• All 41 skills: updated input handling to "read all before starting work"
• 10 skills with procedural improvements
• New discover-rules skill (rule derivation from domain model artifacts)
• New domain-discovery skill (convergent synthesis from event storming candidates)

Naming Conventions

• Placeholder naming: type_id pattern (feature_id, adr_id, session_id, pm_id, rule_id)
• All filenames use snake_case, doc folders use kebab-case

Other

• Research docs added: Brandolini (2012), Evans (2003), Vernon (2013)
• Added Out Artifact Protocol, cumulative editing rule, file naming rule to AGENTS.md