feat(skills/profiles): add dembrane notion skills and multi-profile runtime support

[dembrane-sam-bot]

What this changes

• adds 6 new Notion and Ops skills to Sam's skills catalog, allowing Sam to handle Notion-scoped internal workflows — dembrane-org, task-management, resource-navigation, decision-flow, meeting-management, and professional-reflections under src/skills/
• all skills have perfectly structured frontmatter with trigger-oriented description and when_to_use fields matching Sam's capabilities — src/skills/*/skill.md
• refactors the codebase to support multiple distinct agent profiles (e.g., sam and oren) via a shared runtime engine
• introduces profile-specific directories under src/profiles/sam/ and src/profiles/oren/ containing their respective identity.md and scope.md files
• introduces SAM_PROFILE env var as a Docker container runtime variable (defaults to sam if not specified)
• updates the system-prompt assembler (assemble_system_prompt in src/runtime/prompts.py) to hot-load the identity and scope corresponding to the active SAM_PROFILE, with safe fallback to top-level files
• implements a boot / status update announcement that posts an active profile status (e.g., Oren last booted 14:32 30/05 - running on <hash> from dembrane/sam) to the broadcast channel upon startup, and attempts to set the bot's custom profile status (best-effort, gracefully handles expected token-type failures for xoxb- tokens)

Context

Added at the request of Sameer (<@U06G1DC1UMQ>) and Jor (<@U06GEBBD55F>) in Slack thread C0B2VBYU79V (ts=1779466069.300759).

• Tier: 1 (propose freely) & 3 (runtime config and daemon updates)

Confidence

Confidence: high. All profile and configuration additions have been verified and structured defensively. The prompt assembler falls back safely to top-level files if a profile is missing. The boot status announcement has a defensive try-except block so it never blocks startup.