Refactor build workflow and update version

Update GitHub Actions workflow to use setup-go v5 and align with latest tooling practices.

Update version to 4.4.15 in version.txt and pkg/obioptions/version.go.

Add comprehensive documentation for the canonical super-kmer strategy, including:
- Analysis of index v1 limitations
- Experimental observations on super-kmer efficiency
- Detailed pipeline for building v3 index
- Explanation of minimizer-canonization
- Description of unitig construction and frequency filtering
- Storage format specifications for v3
- Aho-Corasick matching implementation

This change introduces a major improvement in index compactness and performance through the use of canonical super-kmers, unitigs, and efficient storage formats.

Makefile

@@ -142,8 +142,8 @@ jjpush:
 	jj auto-describe; \
 	echo "$(BLUE)→ Generating release notes from $$previous_tag to current commit...$(NC)"; \
 	if command -v orla >/dev/null 2>&1 && command -v jq >/dev/null 2>&1; then \
-		release_json=$$(ORLA_MAX_TOOL_CALLS=50 jj log -r "$$previous_tag::@" -T 'commit_id.short() ++ " " ++ description' | \
-			orla agent -m ollama:qwen3-coder-next:latest \
+		release_json=$$(jj log -r "$$previous_tag::@" -T 'commit_id.short() ++ " " ++ description' | \
+			ORLA_MAX_TOOL_CALLS=50 orla agent -m ollama:qwen3-coder-next:latest \
 			"Summarize the following commits into a GitHub release note for version $$version. Ignore commits related to version bumps, .gitignore changes, or any internal housekeeping that is irrelevant to end users. Describe each user-facing change precisely without exposing code. Eliminate redundancy. Output strictly valid JSON with no surrounding text, using this exact schema: {\"title\": \"<short release title>\", \"body\": \"<detailed markdown release notes>\"}"); \
 		release_json=$$(echo "$$release_json" | sed -n '/^{/,/^}/p'); \
 		release_title=$$(echo "$$release_json" | jq -r '.title // empty') ; \