Add apex skills admin

[ORAsonjameyer]

This PR adds and refines the Oracle APEX Admin skill guidance for APEX administration workflows.

The skill focuses on APEX-admin-owned work: workspace lifecycle, deployment/import review, runtime monitoring, security guardrails, APEX users, schema mapping, and supported APEX administration APIs.

Key changes:

• Adds a clear APEX Admin identity gate for live MCP-backed work.
• Requires a confirmed non-SYS/SYSTEM APEX admin identity for routine APEX administration.
• Routes SYS/SYSDBA bootstrap-only work, such as INTERNAL/APEX Instance Administrator setup, to the documented apxchpwd.sql path.
• Separates APEX Admin, APEXlang, DB, ORDS, and SQLcl responsibilities.
• Routes APEX application generation or material app artifact changes to apex/apexlang.
• Routes generic DB work such as users, grants, quotas, tablespaces, AWR/ASH, SQL Monitor, wait events, ORDS diagnostics, and SQL tuning to the relevant DB/ORDS skills.
• Adds file-only analysis handling: the skill states when no database access is needed, asks once for additional customer evidence, and asks where analysis output should be saved.
• Strengthens customer-data handling so reports, findings, filenames, paths, and customer-specific evidence are not written into the skill tree.
• Adds and updates monitoring coverage for APEX Activity Log, Page Performance, Debug/Error evidence, background jobs, REST data sources, runtime-risk export review, and AI token monitoring.
• Adds supported-version guidance for APEX 26.1, 24.2, and 24.1 based on the current Oracle APEX support matrix.
• Adds guidance for APEX-managed schema privilege handling via supported APEX APIs instead of manual grant generation.
• Keeps admin helper tools limited to static APEX-admin planning and export-risk scanning.

Validation:

• Reviewed the updated routing and reference files.
• Verified the APEX Admin skill tree has no stale migration links.
• Verified there are no scope conflicts with the DB and APEXlang skills.
• Redundancies are intentionally avoided: when work belongs to DB, ORDS, SQLcl, APEXlang, the APEX Admin skill routes to the owning skill instead of duplicating that guidance.

[neilfernandez]

Just 1 change requested

[martin-bach-oracle]

Change requested by Neil has been implemented. My testing concluded positively, this looks good to me.